Question

Tìm x

9^x-1 = 9

( 6x - 18 ) : 3 + 25 . 2 = 78

Answer 1

\(9^{x-1}=9\)

\(9^{x-1}=9^1\)

\(x-1=1\)

\(x=1+1\)

\(x=2\)

\(\frac{6x-18}{3}+25\times2=78\)

\(\frac{6\left(x-3\right)}{3}+50=78\)

\(2\left(x-3\right)=78-50\)

\(2x-6=28\)

\(2x=28+6\)

\(2x=34\)

\(x=\frac{34}{2}\)

\(x=17\)

Answer 2

a) \(9^{x-1}=9\)

\(\Rightarrow x-1=1\)

\(\Rightarrow x=2\)

Vậy \(x=2\)

b) \(\left(6x-18\right):3+25.2=78\)

\(\Rightarrow3\left(2x-6\right):3+50=78\)

\(\Rightarrow2x-6=38\)

\(\Rightarrow2x=44\)

\(\Rightarrow x=22\)

Vậy \(x=22\)