a. \(3^2.x+2^2.x=26.2^2-13\)
\(=x.\left(3^2+2^2\right)=26.4-13\)
\(\Rightarrow x.\left(9+4\right)=104-13\)
\(\Rightarrow x.13=91\)
\(\Rightarrow x=91:13=7\)
Vậy-...
b. \(\left(2x-1\right)^2=49\)
\(\Rightarrow\left(2x-1\right)^2=\left(\pm7\right)^2\)
\(\Rightarrow\left[{}\begin{matrix}2x-1=7\\2x-1=-7\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}2x=8\\2x=-6\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=4\\x=-3\end{matrix}\right.\)
Vậy--
c. \(50-5\left(x+4\right)=15\)
\(\Rightarrow5\left(x+4\right)=50-15=35\)
\(\Rightarrow\left(x+4\right)=35:5=7\)
\(\Rightarrow x=7-4=3\)
Vậy-..
d. \(4.\left[\left(30+3^3\right):10+97\right]-300\)
\(=4.\left[\left(30+9\right):10+97\right]-300\)
\(=4.\left[39:10+97\right]-300\)
\(=4.\left[\dfrac{39}{10}+97\right]-300\)
\(=4.\left[\dfrac{1009}{10}\right]-300\)
\(=\dfrac{2018}{5}-300\)
\(=\dfrac{518}{5}\)
e.\(2^3-5^3:5^2:5^2.2^2\)
\(=2^3-5^{-1}.2^2\)
\(=8-\dfrac{1}{5}.4\)
\(=8-\dfrac{4}{5}\)
\(=\dfrac{36}{5}\)
