HELP WITH MATH!!! 20 points
the questions are solving systems by substitution

Answer:

the answer is 4800

Answer:

What is mental math?

Mental math is definitely what it sounds like—doing math in your head. But it’s also more nuanced than that. Being good at mental math tricks doesn’t mean that you’re able to solve 8974387 x 396 in your head instantly; while cool, that wouldn’t be very practical for daily life. So what does mental math mean?

It really just means being able to calculate in your head. It doesn’t mean you can solve every type of problem every time, nor is it a skill that you either “have” or “don’t have”; it’s a skill that you can learn, practice, and improve so that you can solve a bigger range of problems. And mental math certainly doesn’t have to be entirely in your head, either. Jotting down the numbers you need to remember to give you a head start (no pun intended), or writing down your solutions at each “step,” does not negate the “mental”-ness of the math.

Is mental math useful?

Ask this question again next time you’re trying to figure out a tip or doing any kind of construction or home improvement project! And, in addition to handy practical uses, knowing how to do mental math can also just keep your brain sharp and curb your reliance on calculators. Because, come on, doesn’t it feel good to reach for a calculator only to realize, “Wait, I don’t need it!” and figure out the answer in your head? (Spoiler: It does!) Not to mention knowing how to mentally solve small, simple math problems can save you some steps and help you out if you do need to solve a more complicated, difficult problem. There are always going to be some math problems that it would be silly to not solve with a calculator, but, yes, mental math is useful. And if you’re wondering if math itself is useful, math lessons you’ll actually use in real life.

Step-by-step explanation:

Answer: subtraction property of equality

Step-by-step explanation:

Answer: Each towel costs $1.90

Step-by-step explanation:

$15.20 divided by 8 = $1.90

Answer:

21 calouris

Step-by-step explanation:

5250/250

Answer:

500

Step-by-step explanation:

250 X 7 = 1750

5250 - 1750 = 3500

3500 divided by 7 =500

Answer: rotation of 180' clockwise about the origin and then dilation with a scale factor of -1, centered at the origin

Step-by-step explanation:

Two triangles are congruent if all the corresponding angles are equal, and if the corresponding side lengths are equal.

Now, this means that if we have a given triangle, and we apply a dilation/contraction, then the resultant triangle will have different side lengths than the initial triangle, then those two triangles can not be congruent.

So we can already discard all the options with dilations.

Now, remember how the dilation works.

If we have a point that is at a distance L of the origin, and we do a dilation of scale factor K centered at the origin, then the new distance of the point and the origin will be K*L.

Notice that if the scale factor is equal to 1, then there is no change.

In the options, we have one where the scale factor is -1.

The minus sign means that will cause the enlargement to appear on the other side of the center of enlargement. But the scale factor still is of absolute value 1, so it will not change anything.

Then the only option that not dilates the triangle is:

Rotation of 180' clockwise about the origin and then dilation with a scale factor of -1, centered at the origin

So this is the only transformation that results in a figure congruent to the triangle ABC

Answer:

B.

Step-by-step explanation:

I think its B because the Y comes before the slope

Answer:

c

Step-by-step explanation:

y = mx + b

”m” is the slope, so the slope is -2

”b” is the y - intercept, so the y - intercept is (0 , 1)

Answer: 23+x=6

-23 -23

1x/1 -17/1

x=-17

Step-by-step explanation:

Answer:

Rearrange the equation by subtracting what is to the right of the equal sign from both sides of the equation :

 -6*x-(23)=0  

Step by step explanation :

Pulling out like terms

Pull out like factors :

-6x - 23  =   -1 • (6x + 23)  

Solving a Single Variable Equation:

2.1      Solve  :    -6x-23 = 0  

Add  23  to both sides of the equation :  

                     -6x = 23

Multiply both sides of the equation by (-1) :  6x = -23

Divide both sides of the equation by 6:

                    x = -23/6 = -3.833

Therfor the answer is : x = -23/6 = -3.833

Answer:

Choice D. [tex]y = 0.75\, x + 5[/tex].

Step-by-step explanation:

The general equation for the slope-intercept form of a line in a cartesian plane is [tex]y = m\, x + b[/tex], where:

Start by finding the value of [tex]m[/tex]. The slope of a line is equal to its rise-over-run. For the two points in this question:

Calculate the slope of this line:

[tex]\displaystyle m = \text{slope} = \frac{\text{rise}}{\text{run}} = \frac{-12}{-16} = 0.75[/tex].

The equation of the line becomes:

[tex]y = \underbrace{0.75}_{m}\, x + b[/tex].

Substitute the coordinates of either of the two points to find [tex]b[/tex]. For example, for the first point [tex](12, -4)[/tex], substitute in the following:

The equation becomes:

[tex]-4 = 0.75 \times (-12) + b[/tex].

Solve for the value of [tex]b[/tex]:

[tex]b = 5[/tex].

Hence, the slope-intercept form of this line shall be:

[tex]y = 0.75\, x + 5[/tex].

Answer:

415 ft/s

Step-by-step explanation:

I've attached a diagram showing the triangle formed between the plane, the person and the radio tower.

From the attached diagram, x represents the position between the person and the position on the ground directly below the airplane while s represents the distance between the person and the plane.

The constant elevation remains 4090 ft while the value of x and s varies with time.

Thus, x varies with respect to time as dx/dt while s varies with respect to time as ds/dt.

Now, we are told that the plane is flying at the rate of 700 ft/s. This means that; dx/dt = 700 ft/s

Now we want to find the rate at which the distance between the person and the plane is increasing when the plane passes over the radio tower.

This means that we want to find ds/dt when x = 3010 ft

From pythagoras theorem if x = 3010 ft and the Elevation remains 4090 ft, we can find s as;

s = √(4090² + 3010²)

s = √25788200

s ≈ 5078.21 ft

Since we want to find ds/dt at x = 3010 ft, from the diagram, we can say from pythagoras theorem that;

x² + 4090² = s²

Differentiating x and s with respect to t, we have;

2x(dx/dt) = 2s(ds/dt)

2 will cancel out to give;

x(dx/dt) = s(ds/dt)

ds/dt = (x/s)(dx/dt)

Plugging in 700 for dx/dt, 3010 for x and 5078.21 for s, we have;

ds/dt = (3010/5078.21) × 700

ds/dt ≈ 415 ft/s

Answer:

5 miles

Subtract the 1 dollar for each person from 12. You get ten, and divide ten by two, which is 5

Answer:240 rotations

Step-by-step explanation: 1 rotation/45 seconds * 60 seconds / minute * 60 minutes / hour * 3 hours = 3600*3/45 = 240 rotations

Answer:

4 beats

Step-by-step explanation:

that is a whole note and 4 quarters are equal to one whole

Answer:

B- 44

Step-by-step explanation:

87.5 divided by 2 is 43.75. Since it's a square wall, the length and height are both the same, and since length times height is area, if you divide the area by two, you can get a length of one of the sides. Out of all the answers, 44 is the closest to 43.75.

hope this helped! -brooke :))

Answer:

K(x) =  [tex]\frac{-10}{[1 + (-10x)^2]^{\frac{3}{2} } }[/tex]    ( curvature function)

Step-by-step explanation:

considering the Given function

F(x) = [tex]-5x^2[/tex]

first Determine the value of F'(x)

F'(x) = [tex]\frac{d(-5x^2)}{dy}[/tex]

F'(x) = -10x

next we Determine the value of F"(x)

F"(x) = [tex]\frac{d(-10x)}{dy}[/tex]

F" (x) = -10

To find the curvature function we have to insert the values above into the given formula

K(x)  [tex]= \frac{|f"(x)|}{[1 +( f'(x)^2)]^{\frac{3}{2} } }[/tex]

 K(x) =  [tex]\frac{-10}{[1 + (-10x)^2]^{\frac{3}{2} } }[/tex]    ( curvature function)

Answer:

The answer is D 14^10

Answer:

A

Step-by-step explanation:

Answer:

I think it might be zero

Step-by-step explanation:

you might want to look into this all the way beforyou trust put it into*

Answer:

-7 (Not here)

Step-by-step explanation:

1. A negative plus a negative equals a negative/ a negative minus a positive equals a negative so: -10 -4 = -14

2. -14 + 7 = -7 so your answer is -7 and it's not an answer choice so you would select "Not here"

Answer:

No

Step-by-step explanation:

-8 is less than -4. Negative numbers reverse the logic of positive ones: since positive 8 is more than positive 4, negative 8 is less than negative 4.

Answer:

1.41

Step-by-step explanation:

Answer:

If 10 men dig a ditch in 12 days .

Total man-days required to dig the ditch

= 10 men × 12 days

= 120 man-days

how long would 15 men take to dig it?

No of days required to finish the job by 15 men

= 120 men-days / 15 men

= 8 days

Answer: 8 days will be required to finish the job by 15 men

Step-by-step explanation:

Hope this helps u

Crown me as brainliest:)

Answers:

[tex]\displaystyle \lim_{n \to \infty} \frac{a_n}{b_n} = 6[/tex]

Based on the limit comparison test, the series is convergent

========================================================

Explanation:

As n gets really large, the terms [tex]3^n[/tex] and [tex]3^n-2[/tex] are effectively the same. Taking the limit to infinity of the ratio leads to 1.

In other words,

[tex]\displaystyle \lim_{n \to \infty} \frac{3^n}{3^n-2} = \lim_{n \to \infty} \frac{3^n}{3^n} = 1[/tex]

That -2 doesn't really play a role when n gets very large.

This result is then multiplied by the 6 in the [tex]a_n[/tex] sequence, getting 6 as the final limit we want.

So,

[tex]L = \displaystyle \lim_{n \to \infty} \left(a_n \div b_n\right)\\\\\\L = \displaystyle \lim_{n \to \infty} \left(\frac{6}{3^n-2} \div \frac{1}{3^n}\right)\\\\\\L = \displaystyle \lim_{n \to \infty} \left(\frac{6}{3^n-2} \times \frac{3^n}{1}\right)\\\\\\L = \displaystyle \lim_{n \to \infty} \left(\frac{6*3^n}{3^n-2}\right)\\\\\\[/tex]

[tex]L = \displaystyle 6*\lim_{n \to \infty} \left(\frac{3^n}{3^n-2}\right)\\\\\\L = \displaystyle 6*\lim_{n \to \infty} \left(\frac{3^n}{3^n}\right)\\\\\\L = \displaystyle 6*\lim_{n \to \infty} (1)\\\\\\L = \displaystyle 6*1\\\\\\L = \displaystyle 6\\\\\\[/tex]

Since the limiting value is positive and not infinity, this means that both series [tex]\sum a_n[/tex] and [tex]\sum b_n[/tex] converge or they both diverge.

----------------------------

If we plug n = 2 into the [tex]b_n[/tex] sequence, we get

[tex]b_n = \frac{1}{3^n}\\\\b_2 = \frac{1}{3^2}\\\\b_2 = \frac{1}{9}[/tex]

The first term is a = 1/9

If we plugged n = 3, we would get [tex]b_3 = \frac{1}{27}[/tex]

This shows that the common ratio is r = 1/3

Because -1 < r < 1 is true, we know that the infinite geometric series converges. Therefore, [tex]\sum b_n[/tex] converges. We don't need to find the converging value.

Going back to the limit comparison test, we stated that both [tex]\sum a_n[/tex] and [tex]\sum b_n[/tex] either diverge together or converge together.

We've shown that the b series converges, so the 'a' series must converge as well.

answer:

Juanita spent 1 1/2 times as much as Jared, how much did she spend?

$63

explanation:

one and a half of 42 is: 63

so,

the answer is Juanita spent $63!

Juanita paid $63 for the phone, which is equal to 3/2 of what Jared paid while buying the phone.

Follow these procedures to convert an incorrect fraction to a mixed number:

Given: Jared spent $42 on a cell phone.

We need to determine 1 and 1/2 which is 3/2 of total amount spent by Juanita.

So,

42(3/2) = $63

Therefore, Juanita spent $63 which is  3/2 amount spent by Jared in buying the cell phone.

Learn more about mixed fraction here:

https://brainly.com/question/414559

#SPJ2

Answer:

I believe that your answer is C and Moon.

Answer:

FV= $5,325.8

Step-by-step explanation:

Giving the following information:

Mr. Clopu buys an 18-month CD that pays 4.34% simple interest for $5,000.

To calculate the future value, we need to use the following formula:

FV= (P*r*t) + P

P= $5,000

r= 0.0434/12= 0.00362

t= 18

FV= [(5,000*0.00362)*18] + 5,000

FV= $5,325.8

The value of the CD at the end of its term is $39,060

Given:

Time = 18 month

Principal = $5000

Interest rate = 434%

Future value = ?

Future value = Principal × Rate × Time

= 5,000 × 434% × 18

= 5000 × 434/100 × 18

= 5000 × 4.34 × 18

= 39,060

Therefore, the value of the CD at the end of its term is $39,060

Read more:

https://brainly.com/question/12164462

6 candy boxes

Step-by-step explanation :

Since they both bought their own popcorn that means they both spent $8 on popcorn making that a total of $16. Therefore we now only need to find one variable which is the number of candy boxes that they bought in order to reach the $25 total that they spent. This variable can be represented as x in the following algebraic equation.

(2*8) + 1.50x = 25

16 + 1.50x = 25 ... subtract 16 from both sides

1.50x = 9 ... divide both sides by 1.50

x = 6

Finally, we can see that Billy and Tommy bought a total of 6 candy boxes.

Answer:

This is the answer on Delta Math

Step-by-step explanation:

Answer:

y = -3x + 3

Step-by-step explanation:

Slope = -3

y-intercept = 3

Substitute values into slope intercept form :

y=mx + b

Where :

m= Slope

b = y-intercept

[tex]y = - 3x + 3[/tex]

Answer:  A)    4x -8 = 128  

Step-by-step explanation:

We will represent the amount that the normal bus carries by   n= x  

We will represent  the amount that the large bus carries by  l = 2x  

We will also represent the amount that the small bus carries by  s = x-8  

Now add them to equal to 128.

x + 2x + x -8 = 128    

    4x -8 = 128