Question

If (x+a) is a factor of 2x2+20x+5x+10 find a a

Answer 1

x+a is a factor of 2x²+2ax+5x+10

therefore f(-a)=0;

substituting values,

2(-a)²+2(a)(-a)+5(-a)+10=0

2a²-2a²-5a+10=0

-5a+10=0

therefore a=2