Question

If 3 is a zero of the polynomial $2x^2+x+k$, find the value of k.

Answer 1

Given 3 is a zero of the polynomial
Putting x=3
Equation becomes
$2x^2+x+k$
$2(3{)}^2+3+k$
$2\times 9+3+k=0$
$18+3+k=0$
$k=-21$