若3^x=4,3^y=6,求9^2x-y+27^x-y
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若3^x=4,3^y=6,求9^2x-y+27^x-y
9^2x-y+27^x-y
=9^2x÷9^y-27^x÷27^y
=3^4x÷3^2y-3^3x÷3^3y
=(3^x)^4÷(3^y)^2-(3^x)^3÷(3^y)^3
=256÷36-64÷216
=184/27
再问: 9的2x-y+27的x-y =3^(4x-2y)+3^(3x-3y) =3^4x×3^(-2y)+3^3x×3(-3y) =4^4×6^(-2)+4^3×6^(-3) =200/27 这个错了吗
再答: 哦,对不起,我算错了 前面都对的 就是最后一步=200/27
=9^2x÷9^y-27^x÷27^y
=3^4x÷3^2y-3^3x÷3^3y
=(3^x)^4÷(3^y)^2-(3^x)^3÷(3^y)^3
=256÷36-64÷216
=184/27
再问: 9的2x-y+27的x-y =3^(4x-2y)+3^(3x-3y) =3^4x×3^(-2y)+3^3x×3(-3y) =4^4×6^(-2)+4^3×6^(-3) =200/27 这个错了吗
再答: 哦,对不起,我算错了 前面都对的 就是最后一步=200/27
已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27
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{(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20
4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6
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