Bài 1:
\(75+25\cdot7-247:19\)
\(=25\cdot\left(7+3\right)-13\)
\(=25\cdot\left(3+7\right)-13\)
\(=25\cdot10-13\)
\(=250-13\)
\(=237\)
Bài 2:
c) \(2^5\cdot\left(2x+1\right)+1=41\)
\(\Rightarrow2^5\cdot\left(2x+1\right)=41-1\)
\(\Rightarrow32\cdot\left(2x+1\right)=40\)
\(\Rightarrow2x+1=\dfrac{40}{32}\)
\(\Rightarrow2x=\dfrac{5}{4}-1\)
\(\Rightarrow2x=\dfrac{1}{4}\)
\(\Rightarrow x=\dfrac{1}{4}:2\)
\(\Rightarrow x=\dfrac{1}{8}\)
d) \(2^2\cdot5^2-\left(3x-2\right)^3=6^2\)
\(\Rightarrow10^2-\left(3x-2\right)^3=6^2\)
\(\Rightarrow\left(3x-2\right)^3=10^2-6^2\)
\(\Rightarrow\left(3x-2\right)^3=100-36\)
\(\Rightarrow\left(3x-2\right)^3=64\)
\(\Rightarrow\left(3x-2\right)^3=4^3\)
\(\Rightarrow3x-2=4\)
\(\Rightarrow3x=6\)
\(\Rightarrow x=\dfrac{6}{3}\)
\(\Rightarrow x=2\)
