5*0,<span>14-5*0,23х+3*0,3х+3*0,1=0
</span>0,7-1,15х+0,9х+0,3=0
-0,25х=-1
х=4.
<span>Ответ: 4.</span><span>
</span>
1)((x+y)/(x-y)-(x²-xy+y²)/(x²+xy+y²)=
=[(x+y)(x²+xy+y²)-(x-y)(x²-xy+y²)/[(x-y)(x²+xy+y²)]=
=(x³+x²y+xy²+xy²+x²y+y³-x³+x²y-xy²=x²y-xy²+y³)/(x³-y³)=
=(4x²+2y³)/(x³-y³)=2y(2x²+y²)/(x³-y³)
2)x(y³-x³)/[y(y²-2x²)(y²+2x²)*2y(2x²+y²)/(x³-y³)=-2x/(y²-2x²)=2x/(2x-y)
<span>это просто 3,1415926535…</span>
42+23=65-на второй
65+42=109-на третьей
42+65+109=218-всего