______(a-b)_______(c+d)=c+d-a+b
______(a-b)_______(c+d)=c+d-a+b
(a-b+c-d)(a+b-c-d)=[(a-d)-______][(a-d)+______]
-3xy-x+1=1-(______) a-(b+c-d)=a-b-(_______)
(a+b-c+d)×(a-b+d)等于多少?
( )-(c-d)=(a-c)-(-b+d)
设a,b,c,d为正数,求证(a+c/a+b)+(b+d/b+c)+(c+a/c+d)+(d+b/d+a)≥4
已知a/b=c/d=e/f=2,且b+d+f≠0,则(1)a+c+e/b+d+f=( )(2)a-c+e/b-d+f
比例的和等性质:如果①a:b=c:d,那么(a+b):b=_______②a:b=c:d,那么____=(c-d):b
若a-b=2,b-c=-3,c-d=5,则(a-c)(b-d)______.
[a,b)×[c,d
a,b ,c ,d
a b c d* d_________=d c b a