a) a/b=c/d =>a/b+1=c/d+1=>a+b/b=c+d/d
b)a/b=c/d=>a/c=b/d=(a+b)/(c+d)=(2a+2b)/(2c+2d) 1
a/c=b/d=(a-b)/(c-d)=(5a-5b)/(5c-5d) 2
Từ 1 và 2 ,ta có:
(2a+2b)/(2c+2d)=(5a-5b)/(5c-5d)
cho \(\frac{a}{b}=\frac{c}{d}\)(b,d khác 0)
\(\frac{2a+b}{2a-b}=\frac{2c+d}{2c-d}\)
\(\frac{5a-3b}{3a+2b}=\frac{5c-3d}{3c+2d}\)
Chứng minh:\(\frac{5a+3b}{5c+3d}=\frac{2a-3b}{2c-3d}\) Cho a/b=c/d.
\(Cho\) \(\frac{a}{b}=\frac{c}{d}\)
\(CMR:\)\(a,\frac{5a-3b}{3a+2b}=\frac{5c-3d}{3c+2d}\)
\(b,\frac{2a+b}{a-2b}=\frac{2c+d}{c-2d}\)
a, \(\frac{2a+3b}{2a-3b}=\frac{2c+3d}{2c-3d}\)
b, \(\frac{a^2.b^2}{c^2.d^2}=\frac{a^4+b^4-2a^2b^2}{c^4+d^4-2c^2d^2}\)
c/m nếu a/b=c/d
a)\(\frac{2a+3b}{2a-3b}=\frac{2c+3d}{2c-3d}\)
b)\(\frac{5a^3+3b^6}{11a^2-8b^2}=\frac{5c+3cd}{11c^2-8d^2}\)
Chứng minh rằng nếu \(\frac{a}{b}=\frac{c}{d}\)
a, \(\frac{5a+9c}{5b+9d}=\frac{2a}{2b}\)
b, \(\frac{5a+3b}{3a-3b}=\frac{5c+3d}{5c-3d}\)
giúp mik với ạ
1 a) 2a=3b:5b=7c và 3a +5c-7b=30
b)\(\frac{x-1}{2}=\frac{x+3}{4}=\frac{z-5}{6}\)và 5z-3x-4y=50
c)3x=4y=6z và x-3y+2z=70
d)\(\frac{6}{11}x=\frac{9}{2}y=\frac{18}{5}z\)và x+y+z=20
2 cho \(\frac{a}{b}=\frac{c}{d}\)và a;b;c;d\(\ne\)0
a)\(\frac{a}{a-b}\frac{c}{d}\)
b)\(\frac{ac}{bd}=\frac{a^2+c^2}{b^2+d^2}\)
c)\(\frac{a}{3a+b}=\frac{c}{3c+d}\)
d)\(\frac{a^2-b^2}{c^2-d^2}=\frac{ab}{cd}\)
g)\(\frac{5a+3b}{5c+3b}=\frac{5a-3b}{5c-3d}\)
h)\(\frac{2a+3b}{2a-3d}=\frac{2c+3d}{2c-3d}\)
Chứng minh răngnếu \(\frac{a}{b}=\frac{c}{d}thiA:\frac{a^2+2c^2}{b^2+2d^2}=\left(\frac{a+3c}{b+3d}\right)^2\)
Chứng minh rằng: Nếu \(\frac{a}{c}=\frac{b}{d}\)thì \(\frac{5a+3b}{5a-3b}=\frac{5c+3d}{5c-3d}\)
