Ta có:
\(\frac{a}{b}=\frac{c}{d}\)
\(\Rightarrow\frac{a}{c}=\frac{b}{d}\)
\(\Rightarrow\frac{a}{c}.\frac{a}{c}=\frac{b}{d}.\frac{b}{d}=\frac{a}{c}.\frac{b}{d}\)
\(\Rightarrow\frac{a^2}{c^2}=\frac{b^2}{d^2}=\frac{ab}{cd}=\frac{a^2+b^2}{c^2+d^2}\)
CMR: nếu\(\frac{a}{b}=\frac{c}{d}thì\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}\)
Cmr nếu \(\frac{a}{b}=\frac{c}{d}\)thì \(\frac{a^2+b^2}{c^2+d^2}\)=\(\frac{ab}{cd}\)
CMR nếu \(\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}\)(a,b,c,d khác 0). CMR \(\frac{a}{b}=\frac{c}{d}\)hoặc \(\frac{a}{b}=\frac{d}{c}\)
CMR nếu \(\frac{a}{b}\) = \(\frac{c}{d}\) thì \(\frac{a^2+b^2}{c^2+d^2}\)=\(\frac{ab}{cd}\)
Cho \(\frac{a}{b}=\frac{c}{d}\). CMR:
a) \(\frac{a^2-b^2}{c^2-d^2}=\frac{ab}{cd}\)
b) \(\frac{\left(a-b\right)^2}{\left(c-d\right)^2}=\frac{ab}{cd}\)
Cho : \(\frac{a}{b}=\frac{c}{d}CMR:\)\(\frac{ab}{cd}=\frac{a^2-b^2}{c^2-d^2}v\text{à}\left(\frac{a+b}{c+d}\right)^2=\frac{a^2+b^2}{c^2+d^2}\)
biết:
\(\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}\)
\(CMR:\frac{a}{b}=\frac{c}{d};\frac{a}{b}=\frac{d}{c}\)
Cmr: \(\frac{a}{b}\)=\(\frac{c}{d}\) thì \(\frac{a^2+b^2}{c^2+d^2}\)=\(\frac{ab}{cd}\)
Cho tỉ lệ thức \(\frac{a}{b}=\frac{c}{d}.CMR:\frac{ab}{cd}=\frac{a^2-b^2}{c^2-d^2}\)
