math

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

asked by carol
  1. Solve the equation

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

    posted by Mgraph
  2. 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~ :)

    posted by Jai

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