Original equation: x^2 + 3x - 4 = 0
How I solve by factoring is to take term a and c (as in if you were using the quadratic equation), then multiply them together. We want to find two numbers that multiply to equal the product of a x c, but add up to term b.
Term A: x^2 (1)
Term B: -4
1 x -4 = -4
Factors that have a product of -4 and add up to 3: 4, -1
Factored equation: (x + 4)(x - 1) = 0
Set each factored section equal to 0 and solve for x.
x + 4 = 0
x = -4
x - 1 = 0
x = 1
The correct answer is D. x = 1, -4
Hope this helps!! :)