Factorize:
(x+2)(x2+25)−10x2−20x
(x+2)(x2+25)−10x2−20x=(x+2)(x2+25)−10x(x+2)=(x+2)[x2+25−10x]=(x+2)[(x)2−2×x×5+(5)2]=(x+2)(x−5)2
Solve:
(i)x4−2x2−3=0 (ii) x4−10x2+9=0