Question

Tìm c

( 7x + 2 )^-1 = 3^-2

Answer 1

\(\left(7x+2\right)^{-1}=3^{-2}\\ \dfrac{1}{7x+2}=\dfrac{1}{9}\\ \Leftrightarrow9\cdot1=1\cdot\left(7x+2\right)\\ \Leftrightarrow7x+2=9\\ \Leftrightarrow7x=7\\ \Leftrightarrow x=7:7\\ \Rightarrow x=1\\ Vậyx=1\)

Tìm x chứ bn nhỉ!!!!

Answer 2

\(\left(7x+2\right)^{-1}=3^{-2}\)

\(\Rightarrow\dfrac{1}{7x+2}=\dfrac{1}{3^2}\)

\(\Rightarrow\dfrac{1}{7x+2}=\dfrac{1}{9}\)

\(\Rightarrow7x+2=9\)

\(\Rightarrow x=\left(9-2\right):7=1\)

Vậy x = 1