5 sqrt10 xx 2 sqrt8
= 5 xx sqrt10 xx 2 xx color(green)(sqrt8
Simplifying color(green)(sqrt8 by prime factorising 8 :(expressing 8 as a product of its prime factors)
= 5 xx sqrt10 xx 2 xx color(green)(sqrt (2 * 2 * 2)
= 5 xx sqrt10 xx 2 xx color(green)(sqrt (2 ^2* 2)
= 5 xx sqrt10 xx 2 xx color(green)(2sqrt (2)
= 5 xx 2 xx 2 xx sqrt10 xx sqrt (2)
= 20 sqrt (color(blue)(10) xx 2)
= 20 sqrt (color(blue)(5 xx 2) xx 2)
= 20 sqrt ( 5 xx 2^2)
= 20 xx 2 sqrt ( 5)
= 40sqrt ( 5)