a) \(\left|-7^{50}\right|:7^{48}-\left|6^2\right|\)
\(=7^{50}:7^{48}-6^2\)
\(=7^{50-48}-6^2\)
\(=7^2-6^2\)
\(=49-36\)
\(=13\)
b) \(3x-9=\left|-21\right|\)
\(\Rightarrow3x-9=21\)
\(\Rightarrow3x=21+9\)
\(\Rightarrow3x=30\)
\(\Rightarrow x=30:3\)
\(\Rightarrow x=10\)
Vậy \(x=10\)
c) \(\left|x\right|-3=7\)
\(\Rightarrow\left|x\right|=7+3\)
\(\Rightarrow\left|x\right|=10\)
\(\Rightarrow\left[{}\begin{matrix}x=10\\x=-10\end{matrix}\right.\)
Vậy \(x=10\) hoặc \(x=-10\)
d) \(\left|x-4\right|-2=\left|-5\right|\)
\(\Rightarrow\left|x-4\right|-2=5\)
\(\Rightarrow\left|x-4\right|=5+2\)
\(\Rightarrow\left|x-4\right|=7\)
Xét trường hợp 1: \(x-4=7\)
\(\Rightarrow x=7+4\)
\(\Rightarrow x=11\)
Xét trường hợp 2: \(x-4=-7\)
\(\Rightarrow x=-7+4\)
\(\Rightarrow x=-\left(7-4\right)\)
\(\Rightarrow x=-3\)
Vậy \(x=11\) hoặc \(x=-3\)
