Question

x^2-13x+40=0 what are the solutions ?

Answer 1

x=5 v x=8 ... typo :P
simply use Quadratic Formula

Answer 2

(x-8) (x-5) = 0

x=5
x=8

You should really try Wolfram alpha http://www.wolframalpha.com/input/?i=x^2-13x%2B40%3D0#

Answer 3

Factor using which ever preferred method. Since is starts with x^2 each binomial will start with x. since the second +\- symbol is + the symbols will be the same and they will be the first +\- symbol (-)

(x- )(x- )

now we need 2 numbers that multiply to give 40 and add to give us 13. Thats 5 and 8.
(x-5)(x-8)=0
set each equal to 0 and solve.
x-5=0, x=5
x-8=0. x=8
hope this helps