Question

please solve question no. 4.........and 5

Answer 1

a
$a(a - b) = {a}^{2} - ab \\ b(b - c) = {b }^{2} - bc \\ c(c - a) = {c}^{2} - ac \\ sum \: of \: this = {a }^{2} + {b}^{2} + {c}^{2} - ab - bc - ca$