<span>Упростите и найдите числовое значение выражения:
</span>a) x+y)²y /(x-y)(x+y)(x²+y²) +x/(x²+y²) при x =0,3 ; y =1/2
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(x+y)²y /(x-y)(x+y)(x²+y²) +x/(x²+y²) =(x+y)y /(x-y)(x²+y²) +x/<span>(x²+y²) =
</span>(xy+y² +x² -xy)/(x²+y²)(x-y) =(y² +x²)/<span>(x²+y²)(x-y) =1/(x-y)
=1/(0,3 -0,5) = 1/(-0,2) = -5.
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б) (x³+y³) /(x² -y²) -(x²+y²) / (x-y) <span> при x =0,4 ; y =1/2
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(x³+y³) /(x² -y²) -(x²+y²) / (x-y) =(x+y)(x² -xy +y²) /(x-y)(x+y) -<span>(x²+y²) / (x-y) =
</span>(x² -xy +y²) /(x-y) -(x²+y²) / (x-y) = (x² -xy +y² -(<span>x²+y²)) /(x-y) = - xy/(x-y) =
</span>= -0,4*0,5 /(0,4 -0,5) = 0,2/ 0,1 =2.