Question

[Lãnh Hàn Thiên Băng]

Cho a/b=c/d

CMR:

a. (a-b/c-a)^2 =ab/cd

b. (a+b/c+a)^3 = a^3 -b^3/c^3 -d^3

Answer 1

[zZz Cool Kid_new zZz]

\(\frac{a}{b}=\frac{c}{d}=k\)

\(\Rightarrow a=bk;c=dk\)

\(\Rightarrow\frac{a-b}{c-d}=\frac{bk-b}{dk-d}=\frac{b\left(k-1\right)}{d\left(k-1\right)}=\frac{b}{d}\Rightarrow\left(\frac{a-b}{c-d}\right)^2=\frac{b^2}{d^2}\)

=> Sai đề.