Question

If one zero of the quadratic polynomial kx² + 3x + k is 2, then the value of k is

(a) $\frac{5}{6}$
(b) $\frac{-5}{6}$
(c) $\frac{6}{5}$
(d) $\frac{-6}{5}$

Answer 1

$$\begin{gathered} \left(\text{d}\right)\frac{-6}{5} \\ \begin{array}{l}\text{Since 2 is a zero of}k{x}^2+3x+k,\text{we have:}\\ \end{array} \\ k\times {\left(2\right)}^2+3\times 2+k=0 \\ =>4k+k+6=0 \\ =>5k=-6 \\ =>k=\frac{-6}{5} \end{gathered}$$