\(7^{2x+1}.7=1\\ 7^{2x+2}=7^0\\ \Rightarrow2x+2=0\\ 2\left(x+1\right)=0\\ \Rightarrow x+1=0\\ \Rightarrow x=-1\)
Vậy x = -1
Cách khác:
\(7^{2x+1}.7=1\)
\(\Rightarrow7^{2x+1}=1:7\)
\(\Rightarrow7^{2x+1}=\frac{1}{7}\)
\(\Rightarrow7^{2x+1}=7^{-1}\)
\(\Rightarrow2x+1=-1\)
\(\Rightarrow2x=\left(-1\right)-1\)
\(\Rightarrow2x=-2\)
\(\Rightarrow x=\left(-2\right):2\)
\(\Rightarrow x=-1\)
Vậy \(x=-1.\)
Chúc bạn học tốt!
(7^2x+1).7=1
7^2x+2=1
7^2x+2=7^0
\(\Rightarrow\)2x+2=0
2x+2.1=0
2.(x+1)=0
x+1=0:2
x+1=0
x=0-1
x=-1
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