Question

How do you solve `x^2 - 9x - 10 = 0`?

Answer 1

`color(green)( x= -1 , x=10`

Explanation:

`x^2 - 9x - 10 = 0`
We can first factorise this expression and then proceed towards finding the solution:

factorising by : splitting the middle term
`x^2 color(blue)(-9x) - 10 = 0`
`x^2 color(blue)(- 10x + x) - 10 = 0`
`x( x- 10) +1 (x - 10) = 0`
`color(green)((x+1) ( x- 10)) = 0`

Equating the factors with zero to obtain solutions:
`x+1 = 0` and `x-10 = 0`

So, the solutions are:
`color(green)( x= -1 , x=10`