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
-2 ≤ x < 8 is the answer.
Looking at the slope of the "best-fit" line, you can see that for every two hours of homework, 15 more points are scored. (compare t=0 to t=2).
For t=5, the line seems to go through 47.5. So for t=7, which is two hours more, you'd expect a score of 47.5+15 = 62.5.
That answer is in the list, so I'd choose that.
In reality, you would never be able to have any score you like just by putting more hours in, so this can never be a straight line forever...
Answer:
x = 0.75
Step-by-step explanation:
Simplifying
(7x + -5) + -1(3x + -2) = 0
Reorder the terms:
(-5 + 7x) + -1(3x + -2) = 0
Remove parenthesis around (-5 + 7x)
-5 + 7x + -1(3x + -2) = 0
Reorder the terms:
-5 + 7x + -1(-2 + 3x) = 0
-5 + 7x + (-2 * -1 + 3x * -1) = 0
-5 + 7x + (2 + -3x) = 0
Reorder the terms:
-5 + 2 + 7x + -3x = 0
Combine like terms: -5 + 2 = -3
-3 + 7x + -3x = 0
Combine like terms: 7x + -3x = 4x
-3 + 4x = 0
Solving
-3 + 4x = 0
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '3' to each side of the equation.
-3 + 3 + 4x = 0 + 3
Combine like terms: -3 + 3 = 0
0 + 4x = 0 + 3
4x = 0 + 3
Combine like terms: 0 + 3 = 3
4x = 3
Divide each side by '4'.
x = 0.75
Simplifying
x = 0.75
Answer:
C is the correct answer cos it is paid by the customer
