Cho \(\frac{a}{b}=\frac{c}{d}\).Chứng minh:
- 1)\(\frac{a+c}{b+d}=\frac{a-c}{b-d}\)
- 2)\(\frac{a-c}{a+c}=\frac{b-d}{b+d}\)
- 3)\(\frac{a}{a+c}=\frac{b}{b+d}\)
- 4)\(\frac{a}{a-c}=\frac{b}{b-d}\)
- 5)\(\frac{c}{a+c}=\frac{d}{b+d}\)
- 6)\(\frac{c}{a-c}=\frac{d}{b-d}\)
1) \(\frac{a}{b}=\frac{c}{d}=\frac{a+c}{b+d}=\frac{a-c}{b-d}\)
2)\(\frac{a-c}{b-d}=\frac{a+c}{b+d}\Rightarrow\frac{a-c}{a+c}=\frac{b-d}{b+d}\)
3) \(\frac{a}{b}=\frac{c}{d}=\frac{a+c}{b+d}\Rightarrow\frac{a}{a+c}=\frac{b}{b+d}\)
4)\(\frac{a}{b}=\frac{c}{d}=\frac{a-c}{b-d}\Rightarrow\frac{a}{a-c}=\frac{b}{b-d}\)
5)\(\frac{a}{b}=\frac{c}{d}=\frac{a+c}{b+d}\Rightarrow\frac{c}{a+c}=\frac{d}{b+d}\)
6)\(\frac{a}{b}=\frac{c}{d}=\frac{a-c}{b-d}\Rightarrow\frac{c}{a-c}=\frac{d}{b-d}\)
Sử dụng t/c dãy tỉ số=nhau + hoán vị trung tỉ