How do you factor completely x square+5x-6

I'm assuming the "squared" is x^2+5x-6 in which case the answer is (x+6) (x-1)

You find two numbers that add up to the 5 and multiply to the - 6.

It looks like 6 and - 1 can do the job ...

adding: 6 + (-1) = 5

multiplying: 6 x (-1) = - 6.

See? OK. So now, the factors of the expression are

==> (x plus one of the numbers)

and

==> (x plus the other number).

(x + 6) (x - 1) = x² + 5x - 6