[30分][急]a,b,c,d成g.p.试证(a+b+c+d)^2=(a+b)^2+(c+d)^2+2(b+c)^2
已知a/b=c/d,求证a+2b/b=c+2d/d
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 × 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
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
(a/(b+2c+3d))+(b/(c+2d+3a))+(c/d+2a+3b))+(d/(a+2b+3c))>=2/3
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
2(a b)-c.d怎么算
a,b,c,d>0 求证:a/(b+c)+b/(c+d)+c/(d+a)+d/(a+b)大于等于2,怎么证明,
A×2=a B×4=b C×6=c D×12=d A+B+C+D=256 a+b+c+d=770 求A·B`C`D和a`
若a-b=-3,c+d=2,求(b+c)-(a-d)的值