Question

so sánh: \(\left(\dfrac{16}{25}\right)^{10}\) và\(\left(\dfrac{3}{7}\right)^{40}\)

Answer 1

Ta có :

\(\left(\dfrac{16}{25}\right)^{10}=\left(\left(\dfrac{4}{5}\right)^2\right)^{10}=\left(\dfrac{4}{5}\right)^{20}\)

\(\dfrac{3}{7}< \dfrac{4}{5}< 1\Rightarrow\left(\dfrac{3}{7}\right)^{40}< \left(\dfrac{4}{5}\right)^{40}< 1\)

Mà \(\dfrac{4}{5}< 1\Rightarrow\left(\dfrac{4}{5}\right)^{40}< \left(\dfrac{4}{5}\right)^{20}\)

\(\Rightarrow\left(\dfrac{3}{7}\right)^{40}< \left(\dfrac{4}{5}\right)^{20}=\left(\dfrac{16}{25}\right)^{10}\)