2*（a+b+2c+d)=5a;2*（a+b+2c+d)=9b;2*（a+b+2c+d)=15c;2*（a+b+2c+d

A B C D × 9 ___________________ D C B A (1) A = ( )(2) B = ( 已知a/b=c/d,求证a+2b/b=c+2d/d 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 a,b,c,d>0 证(a/(b+2c+3d))+(b/(c+2d+3a))+(c/d+2a+3b))+(d/(a+2b 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 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 已知a-b=3,c +d=2,(b+c )-(a-d)的值为? 已知a-b=-5,b-c=3,求(b-2d+c)-(a-2d+b)