Y = -9x is proportional because its in the format y = kx
if you graph this equation youll see that it is a straight line that passes through the origin
i hope this helps!!
Step-by-step explanation:
It asks you to choose values for w, the width, and evaluate the equation for each. It describes the constraint "the perimeter of 20 units" The perimeter of a rectangle is the length of all the lines of a regtangle.
Or
2L + 2W = 20 reduce this to simplest for by dividing both sides by 2;
L + W = 10, so the length plus the width is 10. Rearrange it to be W = 10 - L. Values of W can range from 1 to 9. Now sove for a few points in the function.
f(W) = 10W - W^2
3; 10(3) - 3^2 = 30 - 9 = 21.
If we look at the constraint, L = 10 - W, when the width is 3 the length must be 7. The area of a rectangle is L x W, 3 x 7 = 21. That checks against the function.
Solve for additional points.
4; 10(4) - 4^2 = 40 - 16 = 24.
If W is 4 the L is 6 and 4 x 6 = 24
Answer:
C)
Step-by-step explanation:
The answer is to the question is C
Answer: f(x) = -0.016x² + 1.6x
Step-by-step explanation:
If the lenght of the road over the arch is 100m, we can consider a coordinate plane and say that the road starts at point (0,0) and finishes at (100,0). The vertice of the parabola is at point (50,40), because the maximum height is 40 and it is always in the middle point of the roots.
So, we have
(0,0) (50,40) (100,0)
A quadratic function is always on the form: f(x) = ax² + bx + c
0 = a0² + b0 + c
40 = a50² + b50 + c
0 = a100² + b100 + c
0 = a0² + b0 + c → c = 0 ∴
40 = a50² + b50
0 = a100² + b100
_________________________
2500a + 50b = 40 (*2)
10000a + 100b = 0
_________________________
5000a + 100b = 80
10000a + 100b = 0 (-)
__________________________
-5000a = 80
-a=80/5000
a=-0.016
∴
2500a + 50b = 40
2500.(-0.016) + 50b = 40
-40 + 50b = 40
50b = 80
b = 80/50
b = 1.6
This way f(x) = -0.016x² + 1.6x