factorize x^2-7x+12
Let's factor in : x2 -7x + 12
Given the quadratic form ax2 + bx + c, you can calculate the discriminant: Δ = b2 -4ac
Δ = (-7)2 -4·1·12
Δ = 49 -4·12
Δ = 49 -48
Δ = 1
As Δ > 0, the equation has two solutions:
Solution first: -b -Δ2a
x1 = 7 -12
x1 = 62
x1 = 3
For the 2nd solution, we obtain: -b + Δ2a
x2 = 7 + 12
x2 = 82
x2 = 4
Result:   (x -3)·(x -4)