Question

Find the value of m if (x+2) is a factor of x^3 - 2mx^2 + 16

Answer 1

(x+2) is a factor of x³ - 2mx² + 16

x+2 = 0 ----» x = -2

x³ - 2mx² + 16 = 0

(-2)³ - 2m(-2)² + 16 = 0

-8 - 2m(4) + 16 = 0

-8m + 8 = 0

8(-m+1) = 0

-m+1 = 0/8

-m + 1 = 0

m = 1

Answer 2

Hi !

p(x) = x³ - 2mx² + 16

(x+2) is a factor of p(x)

so ,

p(-2) = 0
=====================

x³ - 2mx² + 16 = 0

(-2)³ - 2m(-2)² + 16 = 0

-8 - 2m(4) + 16 = 0

-8m + 8 = 0

8 (-m+1) = 0

-m+1 = 0
m = 1