Question

Slove these question plz

Answer 1

$15) \: \: a {}^{2} - b {}^{2} - a - b$


$(a - b)(a + b) - (a + b)$


$(a + b)(a - b - 1)$


$17) \: \: \: a {}^{2} - b {}^{2} + 2bc - c {}^{2}$
$a {}^{2} - (b {}^{2} - 2bc + c {}^{2} )$
${a}^{2} - (b - c) {}^{2}$
$(a - b - c)(a + b - c)$



$19) \: \: \: a {}^{2} + 2ab + b {}^{2} - 9c {}^{2}$
$(a + b) {}^{2} - 9c {}^{2}$
$(a + b + 3c)(a + b - 3c)$


$21) \: \: (a + b) {}^{3} - a - b$

$(a + b) {}^{3} - (a + b)$

$(a + b)((a + b) {}^{2} - 1)$
$(a + b)(a + b + 1)(a + b - 1)$



$23) \: \: x {}^{2} + 2xy + y {}^{2} - a {}^{2} + 2ab - b {}^{2}$

$x {}^{2} + 2xy + y {}^{2} - (a {}^{2} - 2ab + b {}^{2} )$

$(x + y) {}^{2} - (a - b) {}^{2}$

$(x + y + a - b)(x + y - a - b)$


$25) \: \: \: a - b - a {}^{2} + b {}^{2}$


$(a - b)- (a {}^{2} - b {}^{2} )$

$(a - b) - (a - b)(a + b)$

$(a - b)(1 - (a + b))$

$(a - b)(1 - a - b)$


Thanks