x^2+3x-4=50

how do i do this by factoring

I assume you want to solve it.

write it as
x^2 + 3x - 54 = 0
Can you think of two numbers that multiply to get -54 and have a sum of +3 ?
how about +9 and -6 ?

(x+9)(x-6) = 0
x = -9 or x = 6