Cho a/b=c/d chứng minh; a) c/a-c=b/b-d b) a/c= a+b/c+d c) 2.a + 3.a/ 2.b+ 3.d = 2.a – 3.c / 2.b – 3.d

0 bình luận về “Cho a/b=c/d chứng minh; a) c/a-c=b/b-d b) a/c= a+b/c+d c) 2.a + 3.a/ 2.b+ 3.d = 2.a – 3.c / 2.b – 3.d”

1. a. $\frac{a}{b}$ = $\frac{c}{d}$

   <-> $\frac{c}{a}$ = $\frac{d}{b}$

   <-> $\frac{c}{a-c}$ = $\frac{d}{b-d}$

   b. $\frac{a}{b}$ = $\frac{c}{d}$

   <-> $\frac{a}{c}$ = $\frac{b}{d}$= $\frac{a+b}{c+d}$

   c. $\frac{a}{b}$ = $\frac{c}{d}$=$\frac{2a}{2b}$ = $\frac{3c}{3d}$=$\frac{-3c}{-3d}$=$\frac{2a+3c}{2b+3d}$= $\frac{2a-3c}{2b-3d}$

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2. a. abab = cdcd

   <-> caca = dbdb

   <-> ca−cca−c = db−ddb−d

   b. abab = cdcd

   <-> acac = bdbd= a+bc+da+bc+d

   c. abab = cdcd=2a2b2a2b = 3c3d3c3d=−3c−3d−3c−3d=2a+3c2b+3d2a+3c2b+3d= 2a−3c2b−3d2a−3c2b−3d

    

    

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