Question

--)) giúp mk

Answer 1

a, Ta có :

\(\dfrac{a}{c}=\dfrac{c}{b}\Rightarrow ab=c^2\)

\(VT=\dfrac{a^2+c^2}{b^2+c^2}\)

\(=\dfrac{a^2+ab}{b^2+ab}\\ =\dfrac{a\left(a+b\right)}{b\left(b+a\right)}\\ =\dfrac{a}{b}=VP\)

Vậy ...................................

b. Thay x=2 vào A(x) ta có

\(A=2+\dfrac{2^2}{2^2}+\dfrac{2^3}{2^3}+...+\dfrac{2^{2016}}{2^{2016}}\) ( có 2015 phân số)

\(=2+1+1+..+1\\ =2+1\cdot2015\\ =2+2015\\ =2017\)