(1)已知X/3=Y/2=Z/5 求 XY+YZ+ZX/X^2Y^2Z^2 的值 (2)已知1-a/ab =3 求(3a
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(1)已知X/3=Y/2=Z/5 求 XY+YZ+ZX/X^2Y^2Z^2 的值 (2)已知1-a/ab =3 求(3a-1)(3b+1)+1/b-a+12ab的值
![(1)已知X/3=Y/2=Z/5 求 XY+YZ+ZX/X^2Y^2Z^2 的值 (2)已知1-a/ab =3 求(3a](/uploads/image/z/6666379-43-9.jpg?t=%EF%BC%881%EF%BC%89%E5%B7%B2%E7%9F%A5X%2F3%3DY%2F2%3DZ%2F5+%E6%B1%82+XY%2BYZ%2BZX%2FX%5E2Y%5E2Z%5E2+%E7%9A%84%E5%80%BC+%EF%BC%882%EF%BC%89%E5%B7%B2%E7%9F%A51-a%2Fab+%3D3+%E6%B1%82%EF%BC%883a)
1、设x/3=y/2=z/5=k,则x=15k,y=10k,z=25k,所以,(xy+yz+zx)/(x²+y²+z²)=(150k²+250k²+375k²)/(225k²+100k²+625k²)=31/38.
2、(1-a)/ab=3,则ab=(1-a)/3,则[(3a-1)(3b+1)+1]/[b-a+12ab]=[9ab-3b+3a]/[12ab-a+b]=[3(1-a)+3a-3b]/[4(1-a)-a+b]=(3-3b)/(4-5a+b)=……….
2、(1-a)/ab=3,则ab=(1-a)/3,则[(3a-1)(3b+1)+1]/[b-a+12ab]=[9ab-3b+3a]/[12ab-a+b]=[3(1-a)+3a-3b]/[4(1-a)-a+b]=(3-3b)/(4-5a+b)=……….
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(1)已知X/3=Y/2=Z/5 求 XY+YZ+ZX/X^2Y^2Z^2 的值 (2)已知1-a/ab =3 求(3a
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