Question

Find k if x = 3 is a root of equation kx² – 10x + 3 = 0

Answer 1

Given x = 3 is a root of equation kx² – 10x + 3 = 0
So, x = 3 must satisfy the given quadration equation.
$$\begin{gathered} k{\left(3\right)}^2-10\left(3\right)+3=0 \\ \Rightarrow 9k-30+3=0 \\ \Rightarrow 9k-27=0 \\ \Rightarrow 9k=27 \\ \Rightarrow k=\frac{27}{9}=3 \end{gathered}$$
Thus, k = 3.