Question

Только номер 5, пожалуйста!

Answer 1

123123123123123123123123

Answer 2

$5. \\ 1)x ^{2} - y ^{2} + x - y = (x - y)(x + y) + x - y = x + y$

$3)ac {}^{4} - c {}^{4} - ac {}^{2} + c {}^{2} = c {}^{4} (a - 1) - c {}^{2} (a - 1) = (a - 1)(c {}^{4} - c {}^{2} )$