Question

Very-Short-Answer Questions

If $x=\frac{-1}{2}$ is a solution of the quadratic equation $3x^2+2kx-3=0$, find the value of k. [CBSE 2015]

Answer 1

It is given that $x=\frac{-1}{2}$ is a solution of the quadratic equation $3x^2+2kx-3=0$.

$$\begin{gathered} \therefore 3\times {\left(\frac{-1}{2}\right)}^2+2k\times \left(\frac{-1}{2}\right)-3=0 \\ \Rightarrow \frac{3}{4}-k-3=0 \\ \Rightarrow k=\frac{3-12}{4}=-\frac{9}{4} \end{gathered}$$

Hence, the value of k is $-\frac{9}{4}$.