Question

6. Find the function with x-intercepts (-3,0) and (5,0), which also goes through the point (1,8)

Answer 1

Answer:

f(x) = (-1/2)(x^2 + 8x - 15)

Step-by-step explanation:

This function has two roots:  -3 and 5.  Most likely it is a quadratic (all of which have two roots).

Then f(x) = a(x + 3)(x - 5)

The graph goes through (1. 8):  Therefore, y = 8 when x = 1:

f(1) = a(1 + 3)(1 - 5) = 8, or

        a(4)(-4) = 8, or

            -16a = 8, which leads to a = -1/2.

Thus the quadratic in question is f(x) = (-1/2)(x + 3)(x - 5), or

                                                        f(x) = (-1/2)(x^2 + 8x - 15)