Factorise:
x2+1x2−11
x2+1x2−11⇒x2+1x2−2−9⇒(x2+1x2−2)−9⇒(x−1x)2−(3)2⇒(x−1x+3)(x−1x−3)
Factorise: x2+1235x+135
x2+a2+1ax+1
x2+14x2+1−7x−72x