Question

If the equation $9x^2+6kx+4=0$ has equal roots, then the value of k = .

• A. 2 or 0
• B. 2 or 2
• C. -2 or 2

Answer 1

The correct option is C -2 or 2

Given, the roots of quadratic equation $9x^2+6kx+4=0$ are real and equal.

$\text{Discriminant,}\Delta =b^2-4ac\Delta =36k^2–4\left(4\right)\left(9\right)=36k^2–4\left(36\right)$

The roots of quadratic equation are real and equal then $\Delta =036k^2–4\left(36\right)=0k^2-4=0k^2=4k=\sqrt{4}\therefore k=\pm 2$