Algebramedium · Past Paper

Find the value of k if the roots of x^2 - kx + 9 = 0 are equal.

A3
B6
C±6
D±3

✓ Correct Answer: C±6

For equal roots, D = b^2 - 4ac = 0. k^2 - 4(1)(9) = 0 → k^2 = 36 → k = ±6.

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