Question

Решите плииииз, срочно надо

Answer 1

$1) frac{3 x^{2} -xy}{x-y}- frac{2 x^{2} +y ^{2} }{x+y}+ frac{xy}{y+x}= frac{(3 x^{2} -xy)(x+y)-(2 x^{2} +y ^{2})(x-y)+xy(x-y) }{(x-y)(x+y)}= \ = frac{3 x^{3}- x^{2} y+3 x^{2}y -xy ^{2} -2 x^{3}-xy ^{2}+2 x^{2} y+y ^{3} + x^{2} y-xy ^{2} } {(x-y)(x+y)}= \ = frac{ x^{3}+y ^{3}-3xy ^{2} +6 x^{2} y } {(x-y)(x+y)},$            $2) frac{a ^{3 }+b ^{3} }{a+b}+ frac{3a ^{2}b}{a+b}+ frac{3ab ^{2} }{a+b}= frac{a ^{3 }+b ^{3}+3a ^{2}b+3ab ^{2}}{a+b}=(a+b)^{2}$
$3) frac{c^{2} }{d-c}- frac{2cd-d ^{2} }{d-c} = frac{ c^{2}-2cd+d ^{2} }{(d-c)}= frac{(d-c)^{2} }{(d-c)}=d-c$

Answer 2

большое спасибо ,что так быстро)