WAEC - Further Mathematics (2021 - No. 11)

For what value of k is 4x\(^2\) - 12x + k, a perfect square?
-9
\(\frac{-9}{4}\)
\(\frac{9}{4}\)
9

Explanation

4x\(^2\) - 12x + k;

a = 4, b = -12, c = k.

For perfect square  b\(^2\) = 4ac

(-12)\(^2\) = 4 * 4 * k;

144 = 16k

k = 144\16

k = 9

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