Question

Very-Short-Answer Questions

If the roots of the quadratic equation $2x^2+8x+k=0$ are equal then find the value of k. [CBSE 2014]

Answer 1

It is given that the roots of the quadratic equation $2x^2+8x+k=0$ are equal.
$$\begin{gathered} \therefore D=0 \\ \Rightarrow 8^2-4\times 2\times k=0 \\ \Rightarrow 64-8k=0 \\ \Rightarrow k=8 \end{gathered}$$
Hence, the value of k is 8.