For what value of k is 4x\(^2\) - 12x + k, a perfect square?
FURTHER MATHEMATICS
WAEC 2021
For what value of k is 4x\(^2\) - 12x + k, a perfect square?
- A. -9
- B. \(\frac{-9}{4}\)
- C. \(\frac{9}{4}\)
- D. 9
Correct Answer: D. 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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