Question

Hello people ~
factorise: : x^2 – 21x + 108​

Answer 1

$\\ \rm\rightarrowtail x^2-21x+108$

• Use midterm splitation

$\\ \rm\rightarrowtail x^2-12x-9x+108$

$\\ \rm\rightarrowtail x(x-12)-9(x-12)$

$\\ \rm\rightarrowtail (x-9)(x-12)$

Done!