# math

posted by carol

Given the quadratic function f(x) = x2 – 18x + 81, find a value of x such that f(x) = 16.

1. Mgraph

Solve the equation

x^2-18x+81=16
x^2-18x+65=0

2. Jai

f(x) = x^2 – 18x + 81
f(x) = 16
substituting the value of f(x) to the quadratic equation,
16 = x^2 - 18x + 81
0 = x^2 - 18x + 81 - 16
0 = x^2 - 18x + 65
0 = (x-13)(x-5)
thus,
x = 13 and x = 5

hope this helps~ :)

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