Question

The equation x2 – 1x – 90 = 0 has solutions {a, b}. What is a + b?

Answer 1

(x-10)(x+9) =0
×=10 x=-9
10 + (-9)
= 1

Answer 2

The value of a+b is 1.

Explanation:

The given equation is

`x^2-1x-90=0`

It is given that this equation has two solutions {a,b}.

First of all find the factors of given equation. The middle term can be written as -10x+9x.

`x^2-10x+9x-90=0`

`(x^2-10x)+(9x-90)=0`

Taking out common from each parenthesis.

`x(x-10)+9(x-10)=0`

`(x-10)(x+9)=0`

Using zero product property, we get

`x-10=0\Rightarrow x=10`

`x+9=0\Rightarrow x=-9`

The value of a is 10 and b is -9. The sum of both the solutions is

`a+b=10-9=1`

Therefore the value of a+b is 1.