Question

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

Answer 1

x^2 - x - 90 = 0
(x - 10)(x + 9) = 0
x = 10, -9
{10 , -9}
10 + (-9) = 1

probably?
as long as {a,b} aren't coordinates...

Answer 2

The value of a+b is 1.

Explanation:

The given equation is

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

The middle term can be written as -10x+9x.

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

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

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

Using zero product property, equate each factor equal to 0.

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

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

The solutions of the given equation are {-9,10}.

`\{a,b\}=\{-9,10\}`

`a+b=-9+10=1`

Therefore the value of a+b is 1.