Factorise :
(i) 14x3+21x4y−28x2y2 (ii) −5−10t+20t2
{HCF of 14,21,28=7}
(i) 14x3+21x4y−28x2y2
=7x2(2x+3x2y−4y2) [Taking 7x2 as common]
{HCF of 5,10,20=5}(ii) −5−10t+20t2
=−5(1+2t−4t2) [Taking −5 as common]