Question

For what value of k is 3 a zero of the polynomial 2xsquare +x+k ?

Answer 1

P(x)=2x^2 + x +k
P(3)=2(3)^2 + 3 + k

Condition is
P(3)=0
Therefore,
2(3)^2 + 3 + k=0
18+3+k=0
k=-21