- 3 x₂ + 7 x₃ = 3
x₁ + 2 x₂ - x₃ = 0
5 x₁ - 2 x₂ = 3
(a) I suppose this is asking for the determinant of the coefficient matrix.
[tex]\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}[/tex]
Using a cofactor expansion along the first row, this reduces to
[tex]0\begin{vmatrix}2&-1\\-2&0\end{vmatrix}-(-3)\begin{vmatrix}1&-1\\5&0\end{vmatrix}+7\begin{vmatrix}1&2\\5&-2\end{vmatrix}= 3(0 - (-5))+7(-2-10)=\boxed{-69}[/tex]
(b) Using Cramer's rule, we have
[tex]x_1=\dfrac{\begin{vmatrix}\mathbf 3&-3&7\\\mathbf 0&2&-1\\\mathbf 3&-2&0\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]
[tex]x_2=\dfrac{\begin{vmatrix}0&\mathbf 3&7\\1&\mathbf 0&-1\\5&\mathbf 3&0\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]
[tex]x_3=\dfrac{\begin{vmatrix}0&-3&\mathbf 3\\1&2&\mathbf 0\\5&-2&\mathbf 3\end{vmatrix}}{\begin{vmatrix}0&-3&7\\1&2&-1\\5&-2&0\end{vmatrix}}[/tex]
That is, solving for n-th variable consists of dividing [the determinant of the coefficient matrix with its n-th column replaced with the right side of the system, the numbers in boldface,] by [the determinant of the coefficient matrix].
Compute each determinant:
[tex]\begin{vmatrix}\mathbf 3&-3&7\\\mathbf 0&2&-1\\\mathbf 3&-2&0\end{vmatrix}=3\begin{vmatrix}2&-1\\-2&0\end{vmatrix}+3\begin{vmatrix}-3&7\\2&-1\end{vmatrix}=3(0-2)+3(3-14)=-39[/tex]
(expanding along the first column)
[tex]\begin{vmatrix}0&\mathbf 3&7\\1&\mathbf 0&-1\\5&\mathbf 3&0\end{vmatrix}=-1\begin{vmatrix}3&7\\3&0\end{vmatrix}+5\begin{vmatrix}3&7\\0&-1\end{vmatrix}=-1(0-21)+5(-3-0)=6[/tex]
(again, along the first column)
[tex]\begin{vmatrix}0&-3&\mathbf 3\\1&2&\mathbf 0\\5&-2&\mathbf 3\end{vmatrix}=-1\begin{vmatrix}-3&3\\-2&3\end{vmatrix}+5\begin{vmatrix}-3&3\\2&0\end{vmatrix}=-1(-9-(-6))+5(0-6)=-27[/tex]
(first column)
So, we get the solution
[tex]x_1=\dfrac{-39}{-69}=\boxed{\dfrac{13}{23}},x_2=\dfrac6{-69}=\boxed{-\dfrac2{23}},x_3=\dfrac{-27}{-69}=\boxed{\dfrac9{23}}[/tex]
(c) Using elimination:
- 3 x₂ + 7 x₃ = 3
x₁ + 2 x₂ - x₃ = 0
5 x₁ - 2 x₂ = 3
Swap the first two equations:
x₁ + 2 x₂ - x₃ = 0
- 3 x₂ + 7 x₃ = 3
5 x₁ - 2 x₂ = 3
Add -5(equation 1) to equation 3:
x₁ + 2 x₂ - x₃ = 0
- 3 x₂ + 7 x₃ = 3
- 12 x₂ + 5 x₃ = 3
Add -4(equation 2) to equation 3:
x₁ + 2 x₂ - x₃ = 0
- 3 x₂ + 7 x₃ = 3
- 23 x₃ = -9
Multiply through equation 3 by -1/23:
x₁ + 2 x₂ - x₃ = 0
- 3 x₂ + 7 x₃ = 3
x₃ = 9/23
Add -7(equation 3) to equation 2:
x₁ + 2 x₂ - x₃ = 0
- 3 x₂ = 6/23
x₃ = 9/23
Multiply through equation 2 by -1/3:
x₁ + 2 x₂ - x₃ = 0
x₂ = -2/23
x₃ = 9/23
Add -2(equation 2) and equation 3 to equation 1:
x₁ = 13/23
x₂ = -2/23
x₃ = 9/23
Find the value of (27) to the - 2/3
Answer: Yes. For example: (27)^2/3 would be 3^2 which = 9.
Step-by-step explanation: Hopefully this help :D ask for more help if you need!
Jason delivers newspapers on Saturdays and Sundays only. Each newspaper weighs about 1 pound 5 ounces. If he delivers 15 newspapers each day, how much do the two days' worth of newspapers weigh in pounds and ounces?
Answer:
39pounds 6oz
Step-by-step explanation:
15x2=30
1x30=30pounds
5x30=150oz
30p+150oz=39.37500
37500p=6oz
39pounds and 6 oz
Can any one help me?
7th grade math help me plzzz
Answer:
-7 minus 9 = -16
-3-(-10) =7
8-12=-4
4-(-5)=9
Step-by-step explanation:
im in 7th grade on edginuity got it all right
Which two options describe the standard deviation?
The variance square
The extreme distance from the mean expected from the data points
The square root of the variance.
The average distance from the mean expected of the data.
Answer:
The square root of the variance.
The average distance from the mean expected of the data.
Step-by-step explanation:
Standard deviation is a measure of dispersal. It determines the average distance from the mean expected of the data.
Variance is also related to the standard deviationIt is the square root of the variance. The dispersion or variation of a set of values away from the mean is the standard deviation.
Standard deviation = [tex]\sqrt{variance}[/tex]
A survey of 800 school employees yielded the following information: 430 were instructors, 589 were full-time faculty, and 340 of the instructors were full-time faculty. How many school employees were full-time faculty but were not instructors
Answer:
249Step-by-step explanation:
let n(U) be the total number of school employees = 800
Let n(I) be amount of instructors = 430
Let (F) be full-time faculty = 589
Let n(InF) be the instructors who were full-time faculty = 340
The number of employees who were full-time faculty but were not instructors is expressed as:
n(FnI') = n(F) - n(InF)
n(FnI') = 589 - 340
n(FnI') = 249
Hence the number of school employees who were full-time faculty but were not instructors are 249
find two numbers that equal 11,000 when added together, but also equal 3,000 when subtracted from each other
Answer:
4000 and 7000
Step-by-step explanation:
what is 2x + 5x - 11 = -46
Answer: x= -5 hope this helps
Step-by-step explanation:
Given g(x) = -3x + 1, find g(2).
Answer:
- 5
Step-by-step explanation:
Step 1:
g ( x ) = - 3x + 1 Function
Step 2:
g ( x ) = - 3 ( 2 ) + 1 Input x
Step 3:
g ( x ) = - 6 + 1 Multiply
Answer:
g ( x ) = - 5 Add
Hope This Helps :)
A coin is tossed and -sided die numbered 1 through is rolled. Find the probability of tossing a and then rolling a number greater than .
Complete question :
A coin is tossed and a die is rolled. Find the probability of tossing a tail and then rolling a number greater than 2.
Answer : 1/3
Step-by-step explanation:
For a coin :
Sample space = (T, H)
Probability = required outcome / Total possible outcomes
Probability of tail, p(T) = 1 / 2 = 0.5
For a fair die:
Sample space = (1, 2, 3, 4, 5, 6)
Required outcome = number greater than 2 = (3, 4, 5, 6) = 4
P(number greater than 2) = 4/6 = 2/ 3
Hence, probability of a tail, then a number greater than 2 :
(1/2 * 2/3) = 2 /6 = 1/3
From the sum of 3x +4y -3xy and 5x +3y -2xy subtract the sum of 2x +y – 3xy and 10x -9y -8xy.
Answer:
-4x + 16y + 3xy
Step-by-step explanation:
The sum of 3x + 4y - 3xy and 5x + 3y - 2xy is 8x + 7y - 5xy.
The sum of 2x + y - 3xy and 10x - 9y - 8xy is 12x - 8y - 11xy.
Subtract the sum of the second pair from the first pair by changing the sign of the subtrahend. The result is -4x + 16y + 3xy
HELPPPP PLS ASAPPPPP EASY
Answer:
on what
Step-by-step explanation:
??????
Answer:
What do you need help with?
Step-by-step explanation:
Upload a picture
An electronic store sold 6% of the cell phones that were on sale. If only 21 cell phones were sold,
how many cell phones were not sold? Write an equation to solve.
Select the correct choice below and fill in the answer box to complete your choice.
(Type a whole number.)
O A. 21x=0.06; x = 0.06=21; x =
OB. 0.06x = 21; x = 21 -0.06; X=
OC. X=0.06 = 21; x = 21 x 0.06; X=
OD. X-(21 -0.06) = 21; x = 21+ (21 -0.06); x =
There were
cell phones not sold.
(Type a whole number.)
Answer:
The answer is below
Step-by-step explanation:
Let x represent the number of phones that were on sale, given that 6% of the cell phones that were on sale, therefore:
number of cell phones sold = 6% of x = 0.06 × x = 0.06x
21 phones were sold, hence:
0.06x = 21
x = 21/0.06
x = 350 phones
This means that 350 cell phones were on sale.
Number of cell phones not sold = total number of cell phones that were on sale - number of cell phones sold
Number of cell phones not sold = 350 - 21
Number of cell phones not sold = 329
Rectangles P, Q, R, and S are scaled copies of one another. For each pair, decide if the scale factor from one to the other is greater than 1, equal to 1, or less than 1.
The image showing the complete question is attached.
Answer:
1) Scale factor = 2
2) Scale factor = 4
3) Scale factor = ½
4) Scale factor = 2
5) Scale factor = 1
6) Scale factor = ¼
7) Scale factor = 1
Step-by-step explanation:
Scale factor is a number by which the dimensions of an object are multiplied in order to create an enlarged or reduced object.
Now, from the image attached;
1) From P to Q, we see that the length of Q seems to be double that of P. Similarly, the width of Q seems to be double that of P. Thus, each dimension of P is said to be multiplied by 2 to achieve the enlarged dimensions of Q.
Thus, scale factor = 2
2) From P to R, we see that the length of R seems to be 4 times that of P. Similarly, the width of R seems to be 4 times that of P. Thus, each dimension of P is said to be multiplied by 4 to achieve the enlarged dimensions of R.
Thus, scale factor = 4
3) From Q to S, we see that the length of S seems to be half of that of Q. Similarly, the width of S seems to be half of Q. Thus, each dimension of Q is said to be multiplied by ½ to achieve the reduced dimensions of S.
Thus, scale factor = ½
4) From Q to R, we see that the length of R seems to be double that of Q. Similarly, the width of R seems to be double that of Q. Thus, each dimension of Q is said to be multiplied by 2 to achieve the enlarged dimensions of R.
Thus, scale factor = 2
5) From S to P, we can see that the dimensions of both rectangles remain the same. Thus, S was multiplied by a factor of 1 to get P. Scale factor = 1
6) From R to P, we see that the length of P seems to be a quarter that of R. Similarly, the width of P seems to be quarter of R. Thus, each dimension of R is said to be multiplied by ¼ to achieve the reduced dimensions of P.
Thus, scale factor = ¼
7) From P to S, we can see that the dimensions of both rectangles remain the same. Thus, P was multiplied by a factor of 1 to get S. Scale factor = 1
Which of these expressions is the simplified form of the expression (StartFraction sine (x) Over 1 minus cosine squared (x) EndFraction) tangent (StartFraction x Over 2 EndFraction) ?
Answer:
[tex](\frac{sin\ x}{1 - cos^2x})(tan\frac{x}{2}) = \frac{1}{1+cosx}[/tex]
Step-by-step explanation:
Given
[tex](\frac{sin\ x}{1 - cos^2x})(tan\frac{x}{2})[/tex]
Required
Simplify
[tex](\frac{sin\ x}{1 - cos^2x})(tan\frac{x}{2})[/tex]
---------------------------------------------------------------------------------------------------
Considering the denominator of the first bracket
[tex]1 - cos^2x[/tex]
This can be rewritten using different of two squares as follows:
[tex](1 - cosx)(1 + cosx)[/tex]
So, [tex]1 - cos^2x[/tex] can be replaced with [tex](1 - cosx)(1 + cosx)[/tex] in the given expression.
Also, from trigonometry identity
[tex]tan\frac{x}{2} = \frac{1 - cos x}{sin x}[/tex]
So, [tex]tan\frac{x}{2}[/tex] can be replaced with [tex]\frac{1 - cos x}{sin x}[/tex] in the given expression
---------------------------------------------------------------------------------------------------
[tex](\frac{sin\ x}{1 - cos^2x})(tan\frac{x}{2})[/tex] becomes
[tex](\frac{sinx}{(1-cosx)(1+cosx)}) * \frac{1 - cos x}{sin x}[/tex]
[tex](\frac{sinx * (1 - cos x)}{(1-cosx)(1+cosx) * sin x})[/tex]
Cancel out similar expressions
[tex]\frac{1}{1+cosx}[/tex]
The expression cannot be further simplified.
Hence:
[tex](\frac{sin\ x}{1 - cos^2x})(tan\frac{x}{2}) = \frac{1}{1+cosx}[/tex]
The simplified form of the expression :
[tex]\frac{sinx}{1-cos^{2} x} .tan\frac{x}{2} =\frac{1}{1+cosx}[/tex]
We have some trigonometric formula as:
[tex]sin2x=2sinx= cosx\\2cos^{2} x=1+cos2x[/tex]
We have the expression
[tex]\frac{sinx}{1-cos^{2} x} .tan\frac{x}{2} \\=\frac{sinx}{sin^{2} x} .tan\frac{x}{2} \\=\frac{1}{sin x} .tan\frac{x}{2}\\=\frac{1}{2sin \frac{x}{2} cos\frac{x}{2}} .tan\frac{x}{2}\\=\frac{1}{2sin \frac{x}{2} cos\frac{x}{2}} .\frac{sin\frac{x}{2}}{cos\frac{x}{2}} \\=\frac{1}{2cos^{2} \frac{x}{2}}\\=\frac{1}{1+cos{x} }[/tex]
Therefore, the simplified form of the expression is:
[tex]\frac{sinx}{1-cos^{2} x} .tan\frac{x}{2} =\frac{1}{1+cosx}[/tex]
Learn more:https://brainly.com/question/13126358
Can someone help me plz
Answer:
1. Vertex-M sides- LM MN
2. Vertex-D sides- ED CD
3. Vertex-R sides- SR RQ
4. Vertex-T sides- ST TU
5. angle 3 angle D angle CDE
6. angle 4 angle F angle GFE
7. angle 1 angle F angle GFE
8. angle 3 angle I angle HIJ
Consider the function below. Find f(x) = 7
f(x) = 4x - 9
Answer:
x=4
Step-by-step explanation:
it tel you that f(x) = 7 so replace "f(x)" for 7 in the equation. You then get 7 = 4x - 9 so now you solve for x. You have to isolate x so you add 9 to the other side since you do the opposite of -9. Once you add 9 and 7, then divide the answer by 4. You should get 4 = x.
Work:
f(x) = 4x - 9
7 = 4x - 9
7 + 9 = 4x
16 = 4x
16 ÷ 4 = x
4 = x
Which digit is in the tenths place of the number 32.89?
3
2
8
9
Answer:
8 pls brainliest?
Step-by-step explanation: in decimapls the first number to the right of the . Is tenths, next is hundreths
How many pounds are in 80 kilograms?
Answer:
176.37 pounds are in 80 kilograms
Step-by-step explanation:
The kilogram, or kilogramme, is the base unit of weight in the Metric system. It is the approximate weight of a cube of water 10 centimeters on a side.
A pound is a unit of weight commonly used in the United States and the British commonwealths. A pound is defined as exactly 0.45359237 kilograms.
t/8 = -4 find the value of t please :)
Answer:
t = -32
Step-by-step explanation:
I multiplied -4 to 8
Have a wonderful day <33
how do you solve for x
-3x-6y=0
Answer:
x = 2y
Step-by-step explanation:
Simplifying
3x + -6y = 0
Solving
3x + -6y = 0
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '6y' to each side of the equation.
3x + -6y + 6y = 0 + 6y
Combine like terms: -6y + 6y = 0
3x + 0 = 0 + 6y
3x = 0 + 6y
Remove the zero:
3x = 6y
Divide each side by '3'.
x = 2y
Simplifying
x = 2y
Determine the quotient of 2 over 5 divided by 3 over 4
Answer:
8/15
Step-by-step explanation:
600 feet per hour. What is his
speed miles
in
per hour?
Answer:hi
Step-by-step explanation:
Geometric Sequence♡
5, -2, 4/5
the common ratio was 2/5
find the 10th term
Please Answer ASAP!!
Answer:
0.17
Step-by-step explanation:
hope i helped
6th grade math i mark as brainly
Answer:
i got B and D
Step-by-step explanation:
-14 is less then -8 and is left of -8 on a number line.
Help please!!!!!! I can’t figure it out.
Answer:
A.) parallel
Step-by-step explanation:
they are on opposite sides, and will never touch.
Hope I helped!! :)
Kyle plans to estimate the area of the figure below by identifying the full and partial squares that make up the figure.
If Kyle uses the strategy, which statement best describes the figure?
O 20 full squares and 8 partial squares
0 24 full squares and 12 partial squares
0 36 full squares and 12 partial squares
O 40 full squares and 8 partial squares
Answer:
The answer is one hundred percent D
Step-by-step explanation:
Hi
Answer:
D
Step-by-step explanation:
1.5d + 9.25 = 4 + 2.25d
what is d?
.
Answer:
d = 7
Step-by-step explanation:
1.5d + 9.25 = 4 + 2.25d
Combine the constants and the variables.
5.25 = 0.75d
Divide.
d = 7
Archaeologists used pieces of burned wood, or charcoal, found at the site to date prehistoric paintings and drawings on walls and ceilings of a cave in Lascaux, France. Use the information in Example 3 of Section 3.1 to determine the appropriate age of a piece of burned wood, if it was found that 88% of the C-14 found in living trees of the same type had decayed. (Round your answer to the nearest hundred years.) years
Answer:
The age of the wood is [tex] t = 17527.5 \ years [/tex]
Step-by-step explanation:
From the question we are told that 88% of of the C-14 found in living trees of the same type had decayed , this means that the proportion of C-14 that is remaining is mathematically evaluated as
[tex] 1 - 0.88 = 0.12[/tex]
Hence
[tex] N = 0.12N_o[/tex]
Here N represents the remaining C-14 while [tex]N_o[/tex] is the original amount of C-14
Generally the half life of C-14 is [tex]h = 5730 \ years[/tex]
Generally from the formula of radioactive decay
[tex]N = N_o * 2^{-\frac{t}{h} }[/tex]
=> [tex]0.12N_o = N_o * 2^{-\frac{t}{5730} }[/tex]
=> [tex]0.12 = 2^{-\frac{t}{5730} }[/tex]
taking the natural log of both sides
=> [tex] ln [0.12] = ln[ 2^{-\frac{t}{5730} }][/tex]
=> [tex] ln [0.12] = -\frac{t}{5730}ln(2) [/tex]
=> [tex] t = 17527.5 \ years [/tex]
The appropriate age of burned wood will be "17527.5 years".
Radioactive decayAccording to the question,
The proportion of C-14 = 1 - 0.88
= 0.12
then,
N = 0.12 N₀
Now,
The half-life of C-14 will be:
h = 5730 years
By using Radioactive decay formula, we get
→ N = N₀ × [tex](2)^{-\frac{t}{h} }[/tex]
By substituting the values,
0.12N₀ = N₀ × [tex](2)^{-\frac{t}{5730} }[/tex]
0.12 = [tex]2^{-\frac{t}{5730} }[/tex]
By taking "log" both sides,
ln[0.12] = ln[[tex]2^{-\frac{t}{5730} }[/tex]]
ln[0.12] = -[tex]\frac{t}{5730 \ ln(2)}[/tex]
hence,
The age will be:
t = 17527.5 years
Thus the above response is correct.
Find out more information about radioactive decay here:
https://brainly.com/question/1236735