Question

tìm x biết

a)\(\dfrac{x^7}{81}=27\)

b)\(\dfrac{x^8}{9}=729\)

Answer 1

â)\(\dfrac{x^7}{81}=27\Leftrightarrow x^7=27\times81=2187\Leftrightarrow x=3\)

b)\(\dfrac{x^8}{9}=729\Leftrightarrow x^8=729\times9=6561\Leftrightarrow x=3\)

Answer 2

a, \(\dfrac{x^7}{81}=27\)=> x⁷=27. 81=>x⁷=2187=>x=3

b, \(\dfrac{x^8}{9}=729\)=>x⁸=729. 9= 6561=>x=3 hoặc -3

Answer 3

\(\dfrac{x^7}{81}=27\)

\(\Rightarrow x^7=2187\)

\(\Rightarrow x=3\)

\(\dfrac{x^8}{9}=729\)

\(\Rightarrow x^8=6561\)

\(\Rightarrow\left[{}\begin{matrix}x=3\\x=-3\end{matrix}\right.\)