2,7,14,21,294,( ) A.28 B.35 C.273 D.315
3a+b=11 3d+b=11 3b+a=9 a+2b+d=8 a+2c+b=21 a+2b+d=8 b+2d+a=7
a,b,c,d>0 证(a/(b+2c+3d))+(b/(c+2d+3a))+(c/d+2a+3b))+(d/(a+2b
[a,b)×[c,d
a,b ,c ,d
已知a/b=c/d,求证a+2b/b=c+2d/d
求行列式 |a+b+c+2d a b c,d b+c+d+2a b c,d a a+c+d+2b c,d a b a+b
1、已知实数a,b,c,d满足a+b=7,c+d=5,求(a+c)^2+(b+d)^2的最小值.
A B C D × 9 ___________________ D C B A (1) A = ( )(2) B = (
a+b+c+d=2a;a+b+c+d=4b;a+b+c+d=6c;a+b+c+d=8d 求a,b,c,d
A+B+C+D=10 A+B=3 B+D=7 A+A=2 C+1=D谁能算出这个题?
已知:a/b=c/d,求证:(2a+3b)/(a+b)=(2c+3d)/(c+d)
已知a/b=c/d,求证2a+3b/a+b=2c+3d/c+d