x^2 + 3x - 4 = 0
Quadratic formula:
x = -b +- sqrt{b^2 - 4ac}/(2a)
Let a = 1
Let b = 3
Let c = -4
Just plug into the quadratic formula and do the math.
We are looking for x.
x = -3 +- sqrt{3^2 - 4(1)(-4)}/2(1)
x = -3 +- sqrt{9 + 16}/2
x = -3 +- sqrt{25}/2
x = (-3 +- 5)/2
Separate x into two parts.
Part 1
x = (-3 -5)/2
x = (-8)/2
x = -4
Part 2
x = (-3 + 5)/2
x = 2/2
x = 1
Answer: x = -4, x = 1
