X Squared by 2 subtract x subtract 12 equals 0

x^2  -  x   - 12    =   0    factor

(x  - 4) ( x + 3)     =    0

Set both factors to 0  and solve for  x

x  - 4 =   0                 x  + 3     =0 

x  = 4                        x  = -3

X Squared by 2 subtract x subtract 12 equals 0