Question

if 3 is the zero of the polynomial x²+2x-a,then a =?​

Answer 1

Answer:

$x ^{2} + 2x - a = 0$

since x=3 so,

${3}^{2} + 2 \times 3 - a = 0 \\ 9 + 6 - a = 0 \\ 15 - a = 0 \\ - a = - 15 \\ a = 15$

Answer 2

Answer:

P(x) = x² + 2x - a

P(3) = (3)² + 2(3) - a

0 = 9 + 6 - a

a = 15