Question

How do you solve `n^2-9n=-18`?

Answer 1

`n=-3` or `n=6`

Explanation:

Move -18 to the other side of the 'equals to' sign
`n^2 -9n+18 = 0`

Find two numbers which when added/subtracted will give the coefficient of n and when multiplied will give the constant number (which has no variables beside it )
`n^2-6n-3n+18=0`

Then factorise common variables/constants
`n(n-6)+3(n-6)=0`
`(n+3)(n-6)=0`

There are two possible answers
`(n+3)=0` or `(n-6)=0`
So `n=-3` or `n=6`