\(\frac{a}{c}=\frac{b}{d}=>\left(\frac{a}{c}\right)^2=\left(\frac{b}{d}\right)^2\)
\(=>\frac{a^2}{c^2}=\frac{b^2}{d^2}=\frac{a^2+b^2}{c^2+d^2}\)
\(Ta\)\(có\)\(\frac{ab}{cd}=\frac{a}{c}.\frac{b}{d}=\frac{a}{c}.\frac{a}{c}=\frac{a^2}{c^2}\)
\(Suy\)\(ra\)\(\frac{ab}{cd}=\frac{a^2+b^2}{c^2+d^2}\left(đpcm\right)\)
Cho : \(\frac{a}{b}=\frac{c}{d}CMR:\)\(\frac{ab}{cd}=\frac{a^2-b^2}{c^2-d^2}v\text{à}\left(\frac{a+b}{c+d}\right)^2=\frac{a^2+b^2}{c^2+d^2}\)
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 tỉ lệ thức \(\frac{a}{b}=\frac{c}{d}.CMR:\frac{ab}{cd}=\frac{a^2-b^2}{c^2-d^2}\)
cho tỉ lệ thức : \(\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}cmr\frac{a}{b}=\frac{c}{d}\)
Cho\(\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}\)
CMR:\(\frac{a}{b}=\frac{c}{d}\)hoặc \(\frac{a}{b}=\frac{d}{c}\)
Cho:
\(\frac{a^2+b^2}{c^2+d^2}=\frac{ab}{cd}.CMR:\frac{a}{b}=\frac{c}{d}\)
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 \(\frac{a}{b}=\frac{d}{c}\)
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 tỉ lệ thức \(\frac{a}{b}=\frac{c}{d}\)CMR
\(\frac{ab}{cd}=\frac{a^2-b^2}{c^2-d^2}\)và \(\left(\frac{a+b}{c+d}\right)^2=\frac{a^2+b^2}{c^2+d^2}\)
