Question

Thu gọn :

a)\(2^9+2^9=\)

b)\(3^4+3^4+3^4=\)

c)\(A=1+2+2^2+2^3+...+2^{2017}\)

d)\(B=1+3+3^2+...+3^{301}\)

Nếu làm được mình cảm ơn nhé .Hướng dẫn mình cách giải nhé .Cảm ơn nha 

Answer 1

Usako Kinomoto

2⁹ + 2⁹ = 2⁹ x 2 = 2⁹⁺¹ = 2¹⁰ 

Answer 2

Ta có:

\(2^9+2^9=2.2^9\)

\(3^4+3^4+3^4=3.3^4\)

\(A=1+2+2^2+2^3+.....+2^{2017}\)

\(\Rightarrow2A-A=\left(2+2^3+2^4+....+2^{2018}\right)-\left(1+2+2^2+2^3+....+2^{2017}\right)\)

\(\Rightarrow A=2^{2018}-1\)

\(B=1+3+3^2+....+3^{301}\)

\(\Rightarrow3B-B=\left(3+3^3+3^4+.....+3^{302}\right)-\left(1+3+3^2+....+3^{301}\right)\)

\(\Rightarrow B\left(3-1\right)=3^{302}-1\Leftrightarrow B=\frac{3^{302}-1}{3-1}\)