Question

find the value of m the polynomial x³-2mx²+16 is divisible by x+2

Answer 1

x+2=0
so x=-2
x³-2mx²+16=0
substituting -2 in the place of x
(-2)³-2m(-2)²+16=0
-8-8m+16=0
8-8m=0
-8m=-8
m=8÷8=1  (both the negative signs are cancelled out)
therefore the value of m is 1

Answer 2

Given that, the polynomial x³-2mx²+16 is divisible by x+2
So, x+2 must be the factor of given polynomial
x+2=0
x=-2
So, -2 is the zero of given polynomial


x³-2mx²+16 = 0
Replacing x by -2

(-2)³-2m(-2)²+16 = 0 
-8-8m+16 = 0
Taking -8 as common and passed to RHS

-8(1+m-2) = 0
1+m-2 = 0
m-1 = 0
m=1

therefore, the value of m in the given polynomial is 1