\(3.8^x-2.2^{3x}-16=0\)
Đề như thế này ạ
\(3.8^x-2.2^{3x}-16=0\)
\(\Leftrightarrow3.\left(2^3\right)^x-2.2^{3x}=16\)
\(\Leftrightarrow3.2^{3x}-2^{3x}=16\)
\(\Leftrightarrow2^{3x}\left(3-1\right)=16\)
\(\Leftrightarrow2^{3x}.2=16\)
\(\Leftrightarrow2^{3x+1}=2^4\)
\(\Leftrightarrow3x+1=4\)
\(\Leftrightarrow x=1\)
Vậy ....
\(3.8^x-2.2^{3x}-16=0\)
\(\Rightarrow3.8^x-2.8^x=16\)
\(\Rightarrow8^x\left(3-2\right)=16\Rightarrow8^x=16=8^2\)
Vì \(8\ne\pm1;8\ne0\) nên \(x=2\)
Vậy.......
Chúc bạn học tốt!!!
\(3.8^x-2.2^{3x}-16=0\)
\(\Rightarrow3.8^x-2.\left(2^3\right)^x-16=0\)
\(\Rightarrow3.8^x-2.8^x-16=0\)
\(\Rightarrow8^x\left(3-2\right)-16=0\)
\(\Rightarrow8^x-16=0\)
\(\Rightarrow8^x=16\Rightarrow x\in\varnothing\)
Giải lại nà:v
\(3.8^x-2.2^{3x}-16=0\)
\(\Rightarrow3.\left(2^3\right)^x-2.2^{3x}-16=0\)
\(\Rightarrow3.2^{3x}-2.2^{3x}-16=0\)
\(\Rightarrow2^{3x}\left(3-2\right)-16=0\)
\(\Rightarrow2^{3x}-16=0\)
\(\Rightarrow2^{3x}=16=2^4\)
\(\Rightarrow3x=4\Rightarrow x=\dfrac{4}{3}\)
