Question

If one root of the quadratic equation $x^2-7x+k=0$ is $4$, then find the value of $k$.

Answer 1

$x^2-7x+k=0$
${\left(4\right)}^2-7\left(4\right)+k=0$
$\therefore$ $16-28+k=0$
$\therefore$ $-12+k=0$
$\therefore$ $k=12$