- 若a=2,b=4,c=5,且a:b=c:d,则d=______;若xy=43则x-yy=______.
- 若2x-yy=23,则xy=______.
- (a-c):(a+b):(c-b)=2:7:1,且a+b+c=20,则a=______,b=______,c=______.
- 若x2=y3=z4,则x+2y-zx-y+2z=______.
- 若a3=b4=c5≠0,则a-bc=______.
- 若ab=cd=ef=23,则a+3cb+3d=______,c-ed-f=______.
- 若a4=b5=c6,则a+bc-b=______.
- 若x:y:z=2:(-1):1,则x+2y-z2x-y+z=______.
- 若2x-y与x+y的比是2:3,则xy的值是( )A.15B.45C.65D.54
- 已知线段a,b,c,其中c是a和b的比例中项,a=4,b=9,则c等于( )A.4B.6C.9D.36
- 若x=y2=z3,且x+2y-z=4,则x+y+z等于( )A.6B.10C.12D.14
- 如果x-3y=0,且y≠0,那么xy等于( )A.3B.13C.-3D.-13
- 若x3=y4,则下列式子中不正确的是( )A.x-yy=14B.yy-x=4C.x+2yx=113D.x+yy=74
- 若2x-yx+y=23,则xy=( )A.45B.1C.65D.54
- 若ab=23,则a+ba-b=______.