Question

Show (x+3) is a factor of 2x°2-x-21, thence factorise 2x°2 - x-21​

Answer 1

Answer:

x+3=0

x=-3

f(x)=2x^2-x-21

f(-3)=2(-3)^2-(-3)-21

f(-3)=2*9+3-21

f(-3)=18-18

f(-3)=0

Thus,x+3 is a factor of 2x^2-x-21