Question

For what value of 'k' '3' is a root of the equation 2х²+х+k=0.

Answer 1

#AlexaRousey here!!

If 3 is root of 2x^2 +x + k, then

2(3)^2 +3 + k = 0

=) 2(9) + 3 + k = 0

=) 21 + k = 0

=) k = - 21

Thanks!

Answer 2

substitute k=3 in equation
2(3)^2+3+k=0
2(9)+3+k=0
18+3+k=0
21+k=0
k=-21 is answer