\(1\\ a,=\left(452+1348\right)+\left(375+25\right)\\ =1800+400=2200\\ b,=50\left(12+15+63\right)=50\cdot90=4500\\ c,=\left(479-474\right)+\left(925-920\right)=5+5=10\\ d,=\left(100-95\right)+\left(90-85\right)+\left(85-80\right)+\left(80-75\right)+\left(70-65\right)+\left(60-55\right)\\ =5+5+5+5+5+5=30\)
\(a,456-\left(x+23\right)=326\\ \Rightarrow x+23=130\\ \Rightarrow x=107\\ b,\left(5x-15\right)\left(x-4\right)=0\\ \Rightarrow5\left(x-3\right)\left(x-4\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\\ c,89-\left(x-1\right)^3=62\\ \Rightarrow\left(x-1\right)^3=27=3^3\\ \Rightarrow x-1=3\Rightarrow x=4\\ d,x^5-4x^3=0\\ \Rightarrow x^3\left(x-2\right)\left(x+2\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
Bài 1:
a: Ta có: \(452+1348+375+25\)
\(=1800+400\)
=2200
b: Ta có: \(12\cdot50+50\cdot15+63\cdot50\)
\(=50\left(12+15+63\right)\)
\(=50\cdot90=4500\)
c: Ta có: \(\left(479+925\right)-\left(474+920\right)\)
\(=5+5=10\)
d: Ta có: \(100-95+90-85+80-75+70-65+60-55\)
\(=5+5+5+5+5\)
=25
Bài 2:
a: Ta có: \(456-\left(x+23\right)=326\)
\(\Leftrightarrow x+23=130\)
hay x=107
b: ta có: \(\left(5x-15\right)\left(x-4\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=3\\x=4\end{matrix}\right.\)
c: ta có: \(89-\left(x-1\right)^3=62\)
\(\Leftrightarrow x-1=3\)
hay x=4
d: Ta có: \(x^5-4x^3=0\)
\(\Leftrightarrow x^3\left(x-2\right)\left(x+2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=2\\x=-2\end{matrix}\right.\)
