\(\dfrac{a+b}{b+c}=\dfrac{c+d}{d+a}\)
=>(a+b)(d+a)=(c+d)(b+c)
\(\Leftrightarrow ad+a^2+bd+ab=cb+c^2+db+dc\)
\(\Leftrightarrow ad+a^2+ab=cb+c^2+dc\)
\(\Leftrightarrow d\left(a-c\right)+\left(a+c\right)\left(a-c\right)+b\left(a-c\right)=0\)
\(\Leftrightarrow\left(a-c\right)\left(a+b+c+d\right)=0\)
=>a=c hoặc a+b+c+d=0(đpcm)
cho \(\dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{d}\)
CMR : \(\left(\dfrac{a}{b}+\dfrac{b}{c}+\dfrac{c}{d}\right)^2\) = \(\dfrac{a}{d}\)
cho a+b+c+d khác 0 vàti\(\dfrac{b+c+d-a}{a}=\dfrac{c+d+a-b}{b}=\dfrac{d+a+b-c}{c}=\dfrac{a+b+c-d}{d}P=\left(1+\dfrac{b}{a}\right)\left(1+\dfrac{c}{b}\right)\left(1+\dfrac{c}{d}\right)\left(1+\dfrac{a}{d}\right)\)tính P
giúp mk với ạ , xin cảm ơn
Cho các số hữu tỉ x=\(\dfrac{a}{b};y=\dfrac{c}{d};z=\dfrac{a+c}{b+d}\)(a,b,c,d \(\in\) Z ;b>0 ; d>0)
CMR nếu x<y thì x<z<y
Cho \(\dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{d}\) CMR :\(\left(\dfrac{a+b+c}{b+c+d}\right)^3=\dfrac{a}{d}\)
CMR: \(\dfrac{a}{b}=\dfrac{c}{d}\left(b,d\ne0\right)\Rightarrow\dfrac{a}{b}=\dfrac{a+c}{b+d}.\)
Cho \(\dfrac{a}{c}=\dfrac{c}{b}=\dfrac{b}{d}\)
CMR:\(\dfrac{a^3+c^3-b^3}{c^3+b^3-d^3}=\dfrac{a}{d}\)
cho \(\dfrac{a}{b}=\dfrac{c}{d}\)CMR
\(\left(\dfrac{a-b}{c-d}\right)^2=\dfrac{ab}{cd}\)
\(cho\)cho:\(\dfrac{a}{b}=\dfrac{b}{c}=\dfrac{c}{d}.\) cmr: \(\left(\dfrac{a+b+c}{b+c+d}\right)^3=\dfrac{a}{d}\)
Cho \(\dfrac{a}{b}=\dfrac{c}{d}\)
CMR: \(\dfrac{a.c}{b.d}\) = \(\dfrac{a^2+c^2}{b^2+d^2}\)
