How do you factorise x^2 − 7 x + 12?

1 Answer
Mar 25, 2017



It is done by splitting the middle terms such the coefficients ad up to -12 and their product is +12.

In the present case -7x can be split as -3x and -4x. The multiplication of coefficients also gives +12. Accordingly,

#x^2 -7x+12-># #x^2-3x-4x +12#

Now pair up te terms #(x^2-3x) +(-4x +12)

Extract common factors x(x-3)-4(x-3) #-># (x-3)(x-4)