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3 years ago

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Mary Beth would like to buy a more fuel-efficient vehicle instead of driving her mom's gas-guzzler. Assuming she can find a car

that gets 32 miles per gallon (mpg) and her mom's car gets only 16 mpg, how much will she save if she usually drives about 3,000 miles a year and average price of gas is $3.75 a gallon?

1 answer:

ozzi3 years ago

8 0

Answer:

2x as much

Step-by-step explanation:

First write as an equation:

<u>3000/32*3.75 =</u>

3000/16*3.75

Then that equals:

0.5

So that means her mom's car would be half as efficent as the new one

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Write an equation of a parabola that passes through (3,-30) and has x-intercepts of -2 and 18. Then find the average rate of cha

Nookie1986 [14]

Answer:

The equation of the parabola is $y = \frac{2}{5}\cdot x^{2}-\frac{32}{5}\cdot x -\frac{72}{5}$ . The average rate of change of the parabola is -4.

Step-by-step explanation:

We must remember that a parabola is represented by a quadratic function, which can be formed by knowing three different points. A quadratic function is standard form is represented by:

$y = a\cdot x^{2}+b\cdot x + c$

Where:

$x$ - Independent variable, dimensionless.

$y$ - Dependent variable, dimensionless.

$a$ , $b$ , $c$ - Coefficients, dimensionless.

If we know that $(3, -30)$ , $(-2, 0)$ and $(18, 0)$ are part of the parabola, the following linear system of equations is formed:

$9\cdot a +3\cdot b + c = -30$

$4\cdot a -2\cdot b +c = 0$

$324\cdot a +18\cdot b + c = 0$

This system can be solved both by algebraic means (substitution, elimination, equalization, determinant) and by numerical methods. The solution of the linear system is:

$a = \frac{2}{5}$ , $b = -\frac{32}{5}$ , $c = -\frac{72}{5}$ .

The equation of the parabola is $y = \frac{2}{5}\cdot x^{2}-\frac{32}{5}\cdot x -\frac{72}{5}$ .

Now, we calculate the average rate of change ( $r$ ), dimensionless, between $x = -2$ and $x = 8$ by using the formula of secant line slope:

$r = \frac{y(8)-y(-2)}{8-(-2)}$

$r = \frac{y(8)-y(-2)}{10}$

$x = -2$

$y = \frac{2}{5}\cdot (-2)^{2}-\frac{32}{5}\cdot (-2)-\frac{72}{5}$

$y(-2) = 0$

$x = 8$

$y = \frac{2}{5}\cdot (8)^{2}-\frac{32}{5}\cdot (8)-\frac{72}{5}$

$y(8) = -40$

$r = \frac{-40-0}{10}$

$r = -4$

The average rate of change of the parabola is -4.

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3 years ago

What is the volume of a cylinder with base radius 4 and height 7

stealth61 [152]

Answer:

351.86

Step-by-step explanation:

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3 years ago

Read 2 more answers

The coordinate plane below represents a town. Points A through F are farms in the town. graph of coordinate plane. Point A is at

gayaneshka [121]

I made my own graph using the given points. Pls. see attachment.

<span>Part A: Using the graph above, create a system of inequalities that only contains points D and F in the overlapping shaded regions. Explain how the lines will be graphed and shaded on the coordinate grid above.

I used paint program to graph the points based on the given data.
I used a ruler as guide as I draw my line containing both points D and F and extended the line outward.
The yellow lines above represents the shaded portion of the graph.

y = mx + b

b is the y-intercept. It is the value of y when x is 0. In this case, b = 3.5
m is the slope. It is the change in y divided by the change in x.
point D (2,4) ; point F (-2,3)
change in y: 4 - 3 = 1
change in x: 2 - (-2) = 4
m = 1/4

y = 1/4 x + 3.5

Since we are looking for a system of inequality and the portion shaded is in the upper part of the line, the value of y will be greater than or equal to.

y </span>≥ 1/4x + 3.5<span>

Part B: Explain how to verify that the points D and F are solutions to the system of inequalities created in Part A.

To check the solution given above. We will use the x values of points D and F and check whether its y values are equal to or greater than the solution.</span>

y ≥ 1/4x + 3.5

Point D (2,4) : x = 2 : y ≥ 1/4 * 2 + 3.5 → 0.5 + 3.5 → 4
Point F (-2.3): x = -2 ; y ≥ 1/4 * -2 + 3.5 → -0.5 + 3.5 → 3
<span>
Part C: Chickens can only be raised in the area defined by y > 2x − 2. Explain how you can identify farms in which chickens can be raised.

y > 2x - 2

We will get the coordinates of each point and see if its x value will generate the desired value of y.

A(2,-3) ; x = 2 : </span><span>y > 2(2) - 2 </span>→ 4 - 2 → 2 . DID NOT PASS. -3 is lesser than 2.<span>
B(-3,-4) ; x = -3 : y > 2(-3) - 2 </span>→ -6 - 2 → -8. PASSED. -4 is greater than -8.<span>
C(-4,2) ; x = -4 : y > 2(-4) - 2 </span>→ -8 - 2 → -10. PASSED. 2 is greater than -10.<span>
D(2,4) ; x = 2 : y > 2(2) - 2 </span>→ 4 - 2 → 2. PASSED. 4 is greater than 2.<span>
E(3,1) ; x = 3 : y > 2(3) - 2 </span>→ 6 - 2 → 4. DID NOT PASS. 1 is lesser than 4.<span>
F(-2,3) ; x = -2 ; y > 2(-2) - 2 </span>→ -4 - 2 → -6. PASSED. 3 is greater than -6.

Among the farms, points B,C, D, and F can raise chickens based on the given system of linear inequality.

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4 years ago

Expand and simplify x(x + 1)(x + 2)

zimovet [89]

Answer:

$x^3$ + 3 $x^2$ + 2x

Step-by-step explanation:

x(x^2 + x + 2x + 2)

x ( x^2 + 3x + 2)

$x^3$ + 3 $x^2$ + 2x

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user100 [1]

I'm pretty sure this is Triangle stuff, with Sin, Cos + Tan, etc.

I can't remember it all I'm afraid, but the angle will be the 1 degree, 10 minutes - the Hypotenuse side will be the 3.5 km

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3 years ago