Answer:
S7 = 175S17 = 2465Sn = 1/2(n³ +n)Step-by-step explanation:
The progression of sums is ...
1, 5, 15, 34, 65, ...
So, first differences are ...
4, 10, 19, 31
Second differences are ...
6, 9, 12, ...
Third differences are constant:
3, 3, ...
This means the expression for Sn will be a cubic expression. If dn is the first of the n-th differences, then the equation can be written as ...
Sn = S1 +(n -1)(d1 +(n -2)/2(d2 +(n -3)/3(d3)))
And this simplifies a little bit to ...
Sn = 1 +(n -1)(4 +(n -2)(n +3)/2)
In simpler form, we have ...
Sn = 1/2(n³ +n)
Then the two terms we're interested in are ...
S7 = (1/2)(7³ +7) = 175
S17 = (1/2)(17³ +17) = 2465
Each term Sₙ consists of the sum of a triangular number of terms, which are given by
[tex]T_n = \displaystyle \sum_{k=1}^n k = 1 + 2 + 3 + \cdots + n = \frac{n(n+1)}2[/tex]
The triangular numbers are given recursively for n ≥ 1 by
[tex]T_n = T_{n-1} + n[/tex]
starting with T₀ = 0.
For example,
• S₁ = 1 and
[tex]\displaystyle S_1 = \sum_{k=T_0+1}^{T_1} k = \sum_{k=1}^1 k = 1[/tex]
• S₂ = 2 + 3 and
[tex]\displaystyle S_2 = \sum_{k=T_1+1}^{T_2} k = \sum_{k=2}^3 k = 2 + 3[/tex]
• S₃ = 4 + 5 + 6 and
[tex]\displaystyle S_3 = \sum_{k=T_2+1}^{T_3} k = \sum_{k=4}^6 k = 4 + 5 + 6[/tex]
Then the n-th term of the sequence we're considering is
[tex]S_n = \displaystyle \sum_{k=T_{n-1}+1}^{T_n} k = \sum_{k=T_{n-1}+1}^{T_{n-1}+n} k[/tex]
Expanding this sum, we have
[tex]S_n = \left(T_{n-1}+1\right) + \left(T_{n-1}+2\right) + \left(T_{n-1}+3\right) + \cdots + \left(T_{n-1}+n\right)[/tex]
There are n terms on the right side, and hence n copies of [tex]T_{n-1}[/tex], and the rest of the terms make up the next triangular number [tex]T_n[/tex] :
[tex]S_n = nT_{n-1} + 1 + 2 + 3 + \cdots + n[/tex]
[tex]S_n = nT_{n-1} + \displaystyle \sum_{k=1}^n k[/tex]
[tex]S_n = nT_{n-1} + T_n[/tex]
We have a closed form for [tex]T_n[/tex], so we end up with
[tex]S_n = n \cdot \dfrac{(n-1)n}2 + \dfrac{n(n+1)}2 \implies \boxed{S_n=\dfrac{n^3+n}2}[/tex]
From here it's easy to find S₇ and S₁₇.
[tex]S_7 = \dfrac{7^3+7}2 \implies \boxed{S_7 = 175}[/tex]
[tex]S_{17} = \dfrac{17^3+17}2 \implies \boxed{S_{17} = 2465}[/tex]
Grandma Maude wanted a tall cake for her 80th birthday. The baker made a cake with 4x3 – x layers. Each layer was 2 + 3x2 cm. Which expression shows the total height of Grandma Maude’s cake?
Using proportions, it is found that the expression that shows the total height of Grandma Maude’s cake is:
[tex]t = 12x^5 + 5x^3 - 2x[/tex]
This question is solved by proportions, using a rule of three.The measure of one layer, in cm, was of [tex]2 + 3x^2[/tex]. In total, there were [tex]4x^3 - x[/tex] layers.The rule of three is:
1 layer - [tex]2 + 3x^2[/tex] cm
[tex]4x^3 - x[/tex] layers - t cm
Applying cross multiplication:
[tex]t = (4x^3 - x)(2 + 3x^2) = 12x^5 + 5x^3 - 2x[/tex]
To learn more about proportions, you can take a look at https://brainly.com/question/24372153
Answer:
12x5 + 5x3 – 2x cm
Step-by-step explanation:
Algebra 2
K.14
Write a quadratic function with zeroes 2 and 8.
Answer:
[tex]x^{2}[/tex] - 10x + 16
Step-by-step explanation:
If the 0s are 2 and 8, then the factors are (x - 2) and (x - 8)
Multiply them together to get [tex]x^{2}[/tex] - 10x + 16
4.6 + 3.28 + 1.03 = ___
8.91
8.81
8.37
8.18
Answer: The answer is 8.91.
Answer : 8.91
Step - by - step explanation :
Sometimes if a question is to big for you - it's best to start off small . . .
4.60 + 3.28 = 7.88
7.88 + 1.03 = 8.91
John finished his English assignment in 1/3 hours. Then he completed his chemistry assignment in 2/5 hours. What was the total amount of time John spent doing these two assignments?
these two assignments?
Answer: 11/15 hours
Step-by-step explanation:
Find LCD (lowest common denominator)
1/3=5/15
2/5=6/15
6/15+5/15=11/15 hours or 44 minutes
what is the perimeter of a rectangular whose area is 92 square mm and length is 11.5 mm
We are given –
Area of rectangular is = 92 square mmLength of rectangular is = 11.5 mmWe are asked to find out the value of perimeter of the rectangular! Let's find it's breadth first!We know that–
[tex]\qquad[/tex][tex] \purple{\bf\longrightarrow Area_{(Rectangular)} = Length \times Breadth} [/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow 92 = 11.5 \times Breadth [/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Breadth = \cancel{\dfrac{92}{11.5}}[/tex]
[tex]\qquad[/tex][tex] \purple{\bf \longrightarrow Breadth = 8 \: mm}[/tex]
Now, Perimeter of rectangular –
[tex]\qquad[/tex][tex] \pink{\bf \longrightarrow Perimeter _{(Rectangular) } = 2( Length + Breadth) }[/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Perimeter _{(Rectangular) }= 2( 11.5 +8) [/tex]
[tex]\qquad[/tex][tex] \sf \longrightarrow Perimeter _{(Rectangular) } = 2 \times 19.5[/tex]
[tex]\qquad[/tex][tex]\pink{ \bf \longrightarrow Perimeter _{(Rectangular) } = 39\: mm}[/tex]
Henceforth, Perimeter of rectangular is 39mm._______________________________________
Answer:
Perimeter = 39 mmStep-by-step explanation:
In this question we are given with ,
Area of rectangle = 92 sq mmLength of rectangle = 11.5 mmAnd we're asked to find the perimeter of rectangle .
Solution : -
We know that ,
[tex] \pink{ \boxed{\sf{Area \: of \: rectangle = L × W}}}[/tex]
Where ,
L = length of rectangleW = width of rectangleSo from this formula we can find the width of rectangle and equating it with 92 ( because 92 is the given area ) . Substituting value of length :
[tex] \longmapsto \: 11.5 \times W = 92[/tex]
Step 1 : Multiplying 11.5 and W :
[tex] \longmapsto \: 11.5W = 92[/tex]
Step 2 : Dividing by 11.5 on both side :
[tex] \longmapsto \: \frac{ \cancel{11.5}W}{ \cancel{ 11.5}} = \frac{92}{11.5} [/tex]
On further calculations we get :
[tex] \longmapsto \: W = \cancel{\frac{920}{115} }[/tex]
Step 3 : By cancelling 920 by 115 we get :
[tex] \longmapsto \: \purple{\boxed{ \bold{W = 8 \: mm}}}[/tex]
Therefore , width of rectangle is 8 mm .Finding Perimeter :We know that ,
[tex] \blue{ \boxed{ \sf{Perimeter \: of \: rectangle = 2 ( L +W )}}}[/tex]
Where ,
L = Length of rectangle W = Width of rectangleSubstituting values in formula :
[tex] \longrightarrow \: 2(11.5 + 8)[/tex]
Step 1 : Solving parenthesis :
[tex] \longrightarrow \: 2(19.5)[/tex]
Step 2 : Multiplying 2 with 19.5 :
[tex] \longrightarrow \: \green{\boxed{ \bold{39 \: mm}}}[/tex]
Therefore, perimeter of rectangle is 39 mm. #Keep Learning
If f (x) = 3x + 2 and g(x) = x2 – x, find the value.
-
f (2)+1
Answer:
......
Step-by-step explanation:
Sally used a ruler to draw the segment ab she then opened her compass to the length of ab and drew a circle keeping thw compass open to the same length she marked off equal parts along the circle as shown in the following figure using some or all of the points of intersection and point a which of the following regular polygons could she construct
Answer:
Step-by-step explanation:
Equilateral Triangle
Regular Hexagon
what is the equation for: 32 is the sum of a number x and 9
Answer:
x + 9 = 32
Step-by-step explanation:
answer for x is 32 - 9 = 23
Planet Q Is 3.6 x 10^6km
Planet R Is 1.6 x 10^7km
What Is The Shortest Distance Between Planet Q And R (Answer In Standard Form)
I've Been Stuck On This Question For A Vast Amount Of Time.
Answer:
1.64×10⁷ km
Step-by-step explanation:
We know this is a triangle rectangle, so we apply the Pythagorean Theorem
QR=sqrt(PR²+PQ²)
Solving it, we will encounter in
sqrt(2.56×10¹⁴+1.296×10¹³)
to solve it, we need to bring the two numbers at the same power of ten, so we move 1.296 of one place to the left:
sqrt(2.56×10¹⁴+0.1296×10¹⁴)
we can now add the two numbers:
sqrt(2.6896×10¹⁴)
to solve this, we do the square root of 2.6896 and divide 14 by two (the index of the root is 2, so for roots' properties we can divide 14 by 2 - the index)
which gives us
1.64×10⁷
Shayna pays 20 for 5 bottles of juice. What is the unit price for the bottles of juice?
The polygons below are similar. Find the value of y
Answer:
y = 21
Step-by-step explanation:
Simplify the expression. Write your answer as an improper fraction.
-2/3x divided by (-4/9)
Answer:
3/2x
Step-by-step explanation:
−
2
3
x
−
4
9
=
3
2
x
100 POINTS WILL AWARD BRAINLIEST PLEASE HELP
(IMAGE INCLUDED)
In the image below, the m
Answer: 67°.
Step-by-step explanation:
1) m∠PMR=m∠LMN=3x+19°;
2) m∠LMN+m∠LMP=180°, it can be written as 3x+19+9x-31=180;
3) if to solve the equation 3x+19+9x-31=180, then x=16;
4) m∠PMR=3x+19=48+19=67°.
Find x
Linear pairs are supplementary
9x-31+3x+19=18012x-12=180x-1=15x=15+1=16So
opposite angles are equal
m=9(16)-31=144-31=113°A restaurant tablecloth is 98 inches across. What is the approximate circumference?
The circumference of a circle with diameter of 98 in. is about 308 in.
Step-by-step explanation:We know the diameter. Using the diameter, we can find the circumference.
=> Diameter = 98 in.=> Radius = 98/2=> Radius = 49 in.Circumference = 2πr
=> 2 x 22/7 x 49=> 2 x 22 x 7=> 308 in.Conclusion:Therefore, the circumference of a circle with diameter of 98 in. is about 308 in.
Hoped this helped.
[tex]BrainiacUser1357[/tex]
Write a word phrase to represent the numerical expression below.
(7-3) ÷ 2
Answer:
the quantity seven minus three divided by two
Step-by-step explanation:
its math
Pls help with these questions!
Answer:
I don't know sorry
Round 1276 to the nearest ten?
Answer:
1280
Step-by-step explanation:
look at the 6 in the number
is it 4 or less
or is it 5 or more
as the number is 6 ( more than 5)
then you are going to add 1 to the tens
so the final answer is 1280
I really hope this helps and have a great day
PLS HELP GIVING (BRAINLY)
Which statement shows the correct value for the exponential expression 43?
A. 3 x 3 x 3 x 3 = 81
B. 4x3 = 12
C. 4x 4x4 x 4 = 256
D. 4 x 4 x 4 = 64
Answer:
i think D. 4x4x4 = 64 is answer
Step-by-step explanation:
4³ = 4×4×4 = 64
The value of x² – 2yx + y² when x = 1, y = 2 is
[tex]x^2 - 2xy +y^2 = (x-y)^2 = (1-2)^2 = (-1)^2 =1[/tex]
Which property explains why these two expressions are equal? 7 + q + 4 = 4 + 7 + q
i could use help plz
Answer:
6.70
+26.87
33.57
Step-by-step explanation:
Couldn't explain sorry
-hope it helps
atteo spends a total of 38 min exercising. He walks for 6 min to warm up and then runs at a constant rate of 8 min per mile for the rest of the time. Matteo says that he ran 4.75 mi. Is he correct? Explain your reasoning.
Answer:
he is incorrect.
no one can run for 5 miles everyday.
if so, my man atteo is a legend.
One-celled organisms that are more complex than bacteria are called viruses.
Question 6 options:
True
False
Answer:
false
Step-by-step explanation:
bacteria are bigger and more complex than viruses.
Lucas is having yogurt and an apple for a snack. There are five containers of yogurt in the refrigerator three
are raspberry, one is vanilla, and one is peach. There are also two green apples and three red apples.
If he reaches into the refrigerator to get a yogurt without looking, what is the probability that Lucas wis
choose a raspberry yogurt?
Answer:
His probability of getting a raspberry yogurt is 3/5 or 60%.
Step-by-step explanation:
Pls mark brainliest.
Which number comes next in the series? 7, 10, 10, 13, 16, 16,
Answer:
19
Step-by-step explanation:
In the first number, they add three and that number is repeated.
To further explain, the series would continue like this:
7, 10, 10, 13, 16, 16, 19, 22, 22...
Hope this helps! Brainliest would be appreciated!
Which statement is the correct interpretation of the inequality −4 > −5? (5 points)
Question 7 options:
1)
On a number line, −4 is located to the left of 0 and −5 is located to the right of 0.
2)
On a number line, −4 is located to the right of 0 and −5 is located to the left of 0.
3)
On a number line, −4 is located to the right of −5.
4)
On a number line, −4 is located to the left of −5.
Answer:
On a number line, -4 is located to the right of -5
Step-by-step explanation:
Answer:
On a number line, -4 is located to the right of -5.
Step-by-step explanation:
this is correct, also I don't take credit for it the person above me is the original. :)
What is the value of the expression 2z ÷ [z – (z – 4)] when z = 8?
2z ÷ [z – (z – 4)]
Sub z=8 into the expression
2(8) ÷ [8 – (8 – 4)] = 16 ÷ 4
= 4
An office clerk earns $120 for two 4-hour work shifts. How much will she earn
for 15 hours of work?
Answer:
$225
Step-by-step explanation:
$120 for 2 4-hour shifts, $120 in 8 hours
$15 every 1 hour
Money for 15 hours: 15 x 15 = $225
The office clerk earns $225 for 15 hour of work .
What is unitary method?The formula of the unitary method is to find the value of a single unit and then multiply the value of a single unit to the number of units to get the necessary value.
According to the question
An office clerk earns $120 for two 4-hour work shifts.
i.e
In 2 * 4-hour work shifts office clerk earns = $120
or
In 8 hour work shifts office clerk earns = $120
Now ,
By using unitary method
In 1 hour work shifts office clerk earns = $[tex]\frac{120}{8}[/tex]
= $15
Therefore, for 15 hours of work shifts office clerk earns = $15 * 15
= $225
Hence, The office clerk earns $225 for 15 hour of work .
To know more about unitary method here:
https://brainly.com/question/23423168
#SPJ2
Don’t know where to start
Answer:
A = 80π
Step-by-step explanation:
Area of a circle is A = πr²
Area of the the largest circle - Area of the smaller circle = the shaded part.
Largest circle - Area of the smaller circle = Shaded part of circle
A = π(12)² - A = π(8)²
144π - 64π = 80π
Which equation has the same solution as w / 3.9 = 3? A. w+0.6=1.9 B. w-0.6 = 11.1 C. w+1.03=2.93 D. w-1.03=8.24
The equation has the same solution as w / 3.9 = 3 is w+0.6=1.9
Given:
w / 3.9 = 3
cross multiply
w × 3 = 3.9
3w = 3.9
divide both sides by 3
w = 3.9 / 3
w = 1.3
Check all that applies
A. w+0.6=1.9
w = 1.9 - 0.6
w = 1.3
B. w-0.6 = 11.1
w = 11.1 + 0.6
w = 11.7
C. w+1.03=2.93
w = 2.93 - 1.03
w = 1.9
D. w-1.03=8.24
w = 8.24 + 1.03
w = 9.27
Therefore, the equation has the same solution as w / 3.9 = 3 is w+0.6=1.9
Learn more about equation:
https://brainly.com/question/2972832