\(\dfrac{16}{81}=\left(\dfrac{4}{9}\right)^2=\left(\dfrac{2}{3}\right)^4\)
\(\dfrac{16}{81}=\left(\dfrac{-4}{-9}\right)^2=\left(\dfrac{-2}{-3}\right)^4\)
\(\dfrac{16}{81}=\left(\dfrac{-4}{9}\right)^2=\left(\dfrac{-2}{3}\right)^4\)
\(\dfrac{16}{81}=\left(\dfrac{4}{-9}\right)^2=\left(\dfrac{2}{-3}\right)^4\)
\(\dfrac{16}{81}=\left(\dfrac{4}{9}\right)^2=\left(-\dfrac{4}{9}\right)^2=\left(\dfrac{2^2}{3^2}\right)^2=...\)
Bài 29 Viết số dưới dạng một lũy thừa, ví dụ . Hãy tìm các cách viết khác
lời giải:
\(\dfrac{16}{81}=\left(\dfrac{4}{9}\right)^2=\left(-\dfrac{4}{9}\right)^2=\left(\dfrac{2^2}{3^2}\right)^2=\left(\dfrac{2}{3}\right)^4=...\)
\(\dfrac{16}{81}=\left(\dfrac{4}{9}\right)^2=\left(\dfrac{2}{3}\right)^4\\ \dfrac{16}{81}=\left(\dfrac{-4}{-9}\right)^2=\left(\dfrac{-2}{-3}\right)^4\)
Ta có :
Khi viết dưới dạng 1 lũy thừa thì 16/81 có thể viết thành :
( 4/9 )2 ; ( 2/3 )4 ; ( - 4/9 )2 ; ( - 2/3 )4