Answer: The principal amount is P=$1000P=$1000. •
Step-by-step explanation:
Given:
The equation of a line is

To find:
The slope and y-intercept of the line.
Solution:
We have,
...(i)
The slope intercept form of a line is
...(ii)
Where, m is the slope and b is the y-intercept.
On comparing (i) and (ii), we get

Slope of the line = 1
y-intercept of the line = -4
The coordinate form of y-intercept is (0,b). So, the y-intercept of the given line is (0,-4).
Therefore, the slope of the line is 1 and the y-intercept is (0,-4).
First find the secant line. The slope of the secant line through

(when

) and

(when

) is the average rate of change of

over the interval
![[-1,2]](https://tex.z-dn.net/?f=%5B-1%2C2%5D)
:

The tangent line to

will have a slope determined by the derivative:

Both the secant and tangent will have the same slope when

, or when

.
Starting off with the polynomial in standard form would be extremely difficult, but we can construct one fairly easily with the zeroes we've been given.
We know from the given zeroes that our function has the value 0 when x = 1, x = -2, and x = 2. Manipulating each equation, we can rewrite them as x - 1 = 0, x + 2 = 0, and x - 2 = 0. To construct our polynomial, we simply use all three of the expressions on the left side of the equation as factors and multiply them together, obtaining:

Notice that we can easily obtain each our three zeroes by dividing both sides by the two other factors. From here, we just need to expand the left-hand side of the equation. I'll show the work required here:
=0\\ (x^2-x+2x-2)(x-2)=0\\ (x^2+x-2)(x-2)=0\\ (x^2+x-2)x-(x^2+x-2)2=0\\ x^3+x^2-2x-(2x^2+2x-4)=0\\ x^3+x^2-2x-2x^2-2x+4=0\\ x^3+(x^2-2x^2)+(-2x-2x)+4=0\\ x^3-x^2-4x+4=0\\](https://tex.z-dn.net/?f=%28x-1%29%28x%2B2%29%28x-2%29%3D0%5C%5C%0A%5Cbig%5B%28x-1%29x%2B%28x-1%292%5Cbig%5D%28x-2%29%3D0%5C%5C%0A%28x%5E2-x%2B2x-2%29%28x-2%29%3D0%5C%5C%0A%28x%5E2%2Bx-2%29%28x-2%29%3D0%5C%5C%0A%28x%5E2%2Bx-2%29x-%28x%5E2%2Bx-2%292%3D0%5C%5C%0Ax%5E3%2Bx%5E2-2x-%282x%5E2%2B2x-4%29%3D0%5C%5C%0Ax%5E3%2Bx%5E2-2x-2x%5E2-2x%2B4%3D0%5C%5C%0Ax%5E3%2B%28x%5E2-2x%5E2%29%2B%28-2x-2x%29%2B4%3D0%5C%5C%0Ax%5E3-x%5E2-4x%2B4%3D0%5C%5C)
So, in standard form, our cubic polynomial would be
Let the price of the computer = X
Store A is selling it for 25% off, so they are selling it for 75% of the original price, so you have 0.75X
Store B is selling it for 180 less the original price, so you have X - 180
Now set both equations to equal and solve for x:
0.75x = X-180
Subtract 1X from each side:
-0.25x = -180
Divide both sides by -0.25:
x = -180 / -0.25
X = 720
The original price is $720
check:
720 x 0.25 = 180