Question

1. Tìm số tự nhiên n biết

\(\dfrac{\left(-2\right)^n}{-128}=4\)

2. Tính:

\(\dfrac{\left(-\dfrac{1}{2}\right)^{2n}}{\left(-\dfrac{1}{2}\right)^n}\) ( n thuộc Z )

Answer 1

Nguyễn Thanh Hằng

Answer 2

*Thất vọng về you*

\(\dfrac{\left(-2\right)^n}{-128}=4\)

\(\Rightarrow\dfrac{\left(-2\right)^n}{\left(-2\right)^7}=\left(-2\right)^2\)

\(\Rightarrow\left(-2\right)^n=\left(-2\right)^7.\left(-2\right)^2\)

\(\Rightarrow\left(-2\right)^n=\left(-2\right)^9\)

2)\(\dfrac{\left(-\dfrac{1}{2}\right)^{2n}}{\left(-\dfrac{1}{2}\right)^n}=\dfrac{\left(-\dfrac{1}{2}\right)^n.\left(-\dfrac{1}{2}\right)^n}{\left(-\dfrac{1}{2}\right)^n}=\left(-\dfrac{1}{2}\right)^n\)

Answer 3

\(\dfrac{\left(-2\right)^n}{-128}\)=4

Ta có:

(-2)ⁿ = -128 . 4 = -512

Mà -512 = (-2)⁹ => n=9

Vậy n=9