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If f(2x - 1) = 4x² - 4x - 8, then f(5) = [#permalink]
1
Look for patterns as GRE is not a test of your calculation abilities.

\((2x-1)^2 = 4x^2 - 4x + 1\)

Therefore,

\(f(2x-1) = 4x^2-4x-8\) can be written as

\(f(2x-1) = (2x-1)^2 -9 \)

to compensate for the extra constant \(1\) produced by \((2x-1)^2\) along with \(4x^2 - 4x\).

Now,

\(f(5) = 5^2-9 = 25-9 = 16\)

The answer is \(16\)
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