Find x sub 0 given that the rate of change of y=9x^2+2x-15 with respect to x at x=x sub 0 is 5

Question

it says my answer should be a single number

Answer 1

y = 9x^2+2x-15

Given x1 = 0 and x2 = 5

Average rate of change = f(x2)-f(x1)/x2-x1 where x1<x<x2

f(x2) = 9(25)+10-15 = 225+10-15 = 220

f(x1) = 9(0)+0-15 = -15

Average rate of change A(x) = 220-(-15)/5

= 235/5

A(x) = 47