1)
a) \(\left(-175\right)-123+3+175+\left(-3\right)\)
\(=\left[\left(-175\right)+175\right]+\left[3+\left(-3\right)\right]-123\)
\(=0+0-123\)
\(=-123\)
b) \(17.85+15.17-150\)
\(=17.\left(85+15\right)-150\)
\(=17.100-150\)
\(=1700-150\)
\(=1550\)
c) \(176:\left(4.5^2-3.2^2\right)\)
\(=176:\left(4.25-3.4\right)\)
\(=176:\left(100-12\right)\)
\(=176:88\)
\(=2\)
2)
a) \(8-x=-12\)
\(\Rightarrow x=8-\left(-12\right)\)
\(\Rightarrow x=8+12\)
\(\Rightarrow x=20\)
Vậy \(x=20\)
b) \(20+2^3.x=5^2.4\)
\(\Rightarrow20+8.x=25.4\)
\(\Rightarrow20+8.x=100\)
\(\Rightarrow8.x=100-20\)
\(\Rightarrow8.x=80\)
\(\Rightarrow x=80:8\)
\(\Rightarrow x=10\)
Vậy \(x=10\)
c) \(2\left|x-1\right|+5=15\)
\(\Rightarrow2\left|x-1\right|=15-5\)
\(\Rightarrow2\left|x-1\right|=10\)
\(\Rightarrow\left|x-1\right|=10:2\)
\(\Rightarrow\left|x-1\right|=5\)
Xét trường hợp 1: \(x-1=5\)
\(\Rightarrow x=5+1\)
\(\Rightarrow x=6\)
Xét trường hợp 2: \(x-1=-5\)
\(\Rightarrow x=\left(-5\right)+1\)
\(\Rightarrow x=-5+1\)
\(\Rightarrow x=-\left(5-1\right)\)
\(\Rightarrow x=-4\)
Vậy \(x=6\) hoặc \(x=-4\)
