1.已知:1/x-2/y=3,则(4x+13xy-2y)/(y+3xy-2x)=? 2.分解因式:a`2(b-c)+b`2(c-a)+c`2(a-b)=?3.解方程 x`2+1/(x`2)-3.5(x-1/x)+1=04.已知实数属于a、b、c、满足a+b+c=11与1/(a+b)+1/(b+c)+1/(c+a)==13/17,求a/(b+c)+b/(a+c)+c/(a+b)的值.
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![1.已知:1/x-2/y=3,则(4x+13xy-2y)/(y+3xy-2x)=? 2.分解因式:a`2(b-c)+b`2(c-a)+c`2(a-b)=?3.解方程 x`2+1/(x`2)-3.5(x-1/x)+1=04.已知实数属于a、b、c、满足a+b+c=11与1/(a+b)+1/(b+c)+1/(c+a)==13/17,求a/(b+c)+b/(a+c)+c/(a+b)的值.](/uploads/image/z/5921032-40-2.jpg?t=1.%E5%B7%B2%E7%9F%A5%3A1%2Fx-2%2Fy%3D3%2C%E5%88%99%284x%2B13xy-2y%29%2F%28y%2B3xy-2x%29%3D%3F+2.%E5%88%86%E8%A7%A3%E5%9B%A0%E5%BC%8F%3Aa%602%28b-c%29%2Bb%602%28c-a%29%2Bc%602%28a-b%29%3D%3F3.%E8%A7%A3%E6%96%B9%E7%A8%8B+x%602%2B1%2F%28x%602%29-3.5%28x-1%2Fx%29%2B1%3D04.%E5%B7%B2%E7%9F%A5%E5%AE%9E%E6%95%B0%E5%B1%9E%E4%BA%8Ea%E3%80%81b%E3%80%81c%E3%80%81%E6%BB%A1%E8%B6%B3a%2Bb%2Bc%3D11%E4%B8%8E1%2F%28a%2Bb%29%2B1%2F%28b%2Bc%29%2B1%2F%28c%2Ba%29%3D%3D13%2F17%2C%E6%B1%82a%2F%28b%2Bc%29%2Bb%2F%28a%2Bc%29%2Bc%2F%28a%2Bb%29%E7%9A%84%E5%80%BC.)
1.已知:1/x-2/y=3,则(4x+13xy-2y)/(y+3xy-2x)=? 2.分解因式:a`2(b-c)+b`2(c-a)+c`2(a-b)=?3.解方程 x`2+1/(x`2)-3.5(x-1/x)+1=04.已知实数属于a、b、c、满足a+b+c=11与1/(a+b)+1/(b+c)+1/(c+a)==13/17,求a/(b+c)+b/(a+c)+c/(a+b)的值.
1.已知:1/x-2/y=3,则(4x+13xy-2y)/(y+3xy-2x)=? 2.分解因式:a`2(b-c)+b`2(c-a)+c`2(a-b)=?
3.解方程 x`2+1/(x`2)-3.5(x-1/x)+1=0
4.已知实数属于a、b、c、满足a+b+c=11与1/(a+b)+1/(b+c)+1/(c+a)==13/17,求a/(b+c)+b/(a+c)+c/(a+b)的值.
1.已知:1/x-2/y=3,则(4x+13xy-2y)/(y+3xy-2x)=? 2.分解因式:a`2(b-c)+b`2(c-a)+c`2(a-b)=?3.解方程 x`2+1/(x`2)-3.5(x-1/x)+1=04.已知实数属于a、b、c、满足a+b+c=11与1/(a+b)+1/(b+c)+1/(c+a)==13/17,求a/(b+c)+b/(a+c)+c/(a+b)的值.
1.1/x-2/y=3 ,y-2x=3xy
(4x+13xy-2y)/(y+3xy-2x)
=[2(2x-y)+13xy]/(3xy+3xy)
=(-6xy+13xy)/6xy
=7/6
2.a^2(b-c)+b^2(c-a)+c^2(a-b)
=a^2b-a^2c+b^2c-ab^2+ac^2-bc^2
=ab(a-b)-c(a+b)(a-b)+c^2(a-b)
=(a-b)(ab-ca-bc+c^2)
=(a-b)[a(b-c)-c(b-c)]
=(a-b)(a-c)(b-c)
4.a/(b+c)+b/(a+c)+c/(a+b)
=[11-(b+c)]/(b+c)+[11-(a+c)]/(a+c)+[11-(a+b)]/(a+b)
=11/(b+c)-1+11/(a+c)-1+11/(a+b)-1
=11[1/(a+b)+1/(b+c)+1/(c+a)]-3
=11×13/17-3
=92/17
不好意思 .第三题还没做出来...
7/6
1. (1/x-2/y)xy=3xy ——》y-2x=3xy
(4x+13xy-2y)/(y+3xy-2x)
=[2(2x-y)+13xy)/(3xy+3xy)
=(-6xy+13xy)/6xy
=7/6
劝你还是自己动脑筋做 不会就空着
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