1.tìm các số x,y,z biết rằng 1/2x=2/3y=3/4z va x-y=15
2. cho ti le thuc a/b=c/d
chứng minh a+2c/b+2d=a-3c/b-3d
cho ti le thuc a/b=c/d chung minh rang (a+2c)(b+d)=(a+c)(b+2d)
cho ti le thuc a/b=c/d
chung minh rang a+2c/b+2d=a-3c/b-3d
cho ti le thuc a/b=c/d.Chung minh rang :(a+2c)(b=d)=(a+c)(b+2d)
Cho ti le thuc a/b=c/d cmr (a+2c)(b+d)=(a+c)(b+2d)
cho ti le thuc \(\frac{a}{b}=\frac{c}{d}\)chung minh:
\(\frac{5a+2c}{5b+2d}=\frac{a-4c}{b-4d}\)
cho ti le thuc: \(\frac{a}{b}=\frac{c}{d}\). CMR; (a+ 2c)(b+d)= (a+ c)(b+2d)
a/ Cho ti le thuc \(\frac{a}{b}=\frac{c}{d}\)
Chung minh: \(\frac{2a+5b}{3a-7b}=\frac{2c+5d}{3c-7d}\)
b/ Cho ti le thuc: \(\frac{x}{y}=\frac{m}{n}\)
Chung minh; \(\frac{5x+4y}{3x-6y}=\frac{5m+4n}{3m-6n}\)
chung minh rang tu ti le thuc a/b=c/d ta suy ra duoc ti le thuc a/b=a-c/b-d