Question

If (x + a) is a factor of 2x² + 2ax + 5x + 10, find a.

Answer 1

Given  (x + a) is a factor of `f(x) = 2x^2 + 2ax + 5x + 10`.

Let us now divide  `f(x)` by x + a .

We have, 

Now, remainder = 0 

` 10 - 5a = 0` 

` 10 = 5a `

`10/5=a`

`2 =a`

Hence, the value of a is  2 .