Question

8) (a) For what value of k, 3 is a zero of the polynomial 2x² + x + k?
(b) For what value of k, -2 is a zero of the polynomial 3x² + 4x + 2k?
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Answer 1

A) given 3 is the zero of the polynomial p(x)= 2x² + x + k

so p(3) = 2(3)² + 3 + k

18 + 3 + k= 0

k = -21

B) given -2 is the zero of the polynomial f(x) = 3x² + 4x + 2k

so,f(-2) = 3(-2)² + 4(-2) +2k

12 -8 + 2k = 0

2k = -4

k = -2

Answer 2

f(3)=2×3×3+3+k=0

=21+k=0

K=-21

f(-2)=3×(-2)×(-2)+4×(-2)+2×k=0

=12-8+2k=0

=2k=-4

K=-4/2

k=-2