Posted by carol on Monday, May 2, 2011 at 8:09pm.
Given the quadratic function f(x) = x2 – 18x + 81, find a value of x such that f(x) = 16.

math  Mgraph, Monday, May 2, 2011 at 8:22pm
Solve the equation
x^218x+81=16
x^218x+65=0

math  Jai, Monday, May 2, 2011 at 8:29pm
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 = (x13)(x5)
thus,
x = 13 and x = 5
hope this helps~ :)
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