Question

[Adina Phạm]

Tìm n

1/2 x 2^n + 4 x 2^n = 9 x 5^n

Tính hợp lý

a) A= ( 2^8 + 3^8) : ( 2^5 x 2^3)

b) B = ( 2^17 + 17^2) x (9^15 - 15^9) x (4^2 - 2^4)

Answer 1

[Nguyễn Lê Phước Thịnh]

Bài 1: 

\(\Leftrightarrow2^n\cdot\dfrac{9}{2}=9\cdot5^n\)

\(\Leftrightarrow2^n=2\cdot5^n\)

\(\Leftrightarrow2^{n-1}=5^n\)

Bài 2: 

a: \(A=\dfrac{2^8+3^8}{2^8}=1+\dfrac{3^8}{2^8}\)

b: \(B=\left(2^{17}+17^2\right)\cdot\left(9^{15}-15^9\right)\cdot\left(16-16\right)=0\)