Bài 1. Thực hienj phép tính ( Tính hợp lí nếu có thể)
a) -2011 - ( 200 - 2011)
b) (-2)2 - ( - 2000)0 + ( -1)2018 - | - 20|
c) 23 . 18 - 23 . 26 + ( -23) . 2
Bài 2. Tìm số nguyên x, biết :
a) 3x - ( -5) = 20
b) 3 . ( x + 2) = - 4 + ( - 2)3
c) | x - 20 | + ( -4)2 = ( -1)2017 + 33
Bài 3.
a) Tìm các số nguyên x sao cho 3x - 1 chia hết cho x - 1
b) Tìm các số nguyên x, y biết : ( x - 5) . ( y + 1) = 5
a) \(-2011-\left(200-2011\right)\)
\(=-2011-200+2011\)
\(=\left(-2011+2011\right)-200\)
\(=0-200\)
\(=-200\)
b) \(\left(-2\right)^2-\left(-2000\right)^0+\left(-1\right)^{2018}-\left|-20\right|\)
\(=4-1+1-20\)
\(=4-20\)
\(=-16\)
Bài 1 :
\(a)-2011-(200-2011)\)
\(=-2011-(200+2011)\)
\(=(-2011+2011)-200\)
\(=0-200=-200\)
\(b)(-2)^2-(-2000)^0+(-1)^{2018}-\left|-20\right|\)
\(=4-1+1-20\)
\(=4-20=-16\)
\(c)23\cdot18-23\cdot26+(-23)\cdot2\)
\(=23\cdot(18-26)+-(23\cdot2)\)
\(=23\cdot(-8)+(-46)\)
\(=-230\)
Bài 2 : Tìm số nguyên x biết :
\(a)3x-(-5)=20\)
\(\Rightarrow3x+5=20\)
\(\Rightarrow3x=20-5\)
\(\Rightarrow3x=15\Rightarrow x=5\)
\(b)3(x+2)=-4+(-2)^3\)
\(\Rightarrow3(x+2)=-4+(-8)\)
\(\Rightarrow3(x+2)=-12\)
\(\Rightarrow x+2=-12\div3\)
\(\Rightarrow x+2=-4\)
Tự tìm x câu b, và câu c,
Bài 3 tự làm
c) \(23.18-23.26+\left(-23\right).2\)
\(=23\cdot\left(18-26-2\right)\)
\(=23.\left(-10\right)\)
\(=-230\)
a) \(3x-\left(-5\right)=20\)
\(\Leftrightarrow3x=20-5\)
\(\Leftrightarrow3x=15\)
\(\Leftrightarrow x=15\div3\)
\(\Leftrightarrow x=5\)
Vậy x = 5
b) \(3\left(x+2\right)=-4+\left(-2\right)^3\)
\(\Leftrightarrow3x+6=-4-8\)
\(\Leftrightarrow3x+6=-12\)
\(\Leftrightarrow3x=-12-6\)
\(\Leftrightarrow3x=-18\)
\(\Leftrightarrow x=-18\div3\)
\(\Leftrightarrow x=-6\)
Vậy x = - 6
c) \(\left|x-20\right|+\left(-4\right)^2=\left(-1\right)^{2017}+3^3\)
\(\Leftrightarrow\left|x-20\right|+16=-1+27\)
\(\Leftrightarrow\left|x-20\right|+16=26\)
\(\Leftrightarrow\left|x-20\right|=26-16\)
\(\Leftrightarrow\left|x-20\right|=10\)
\(\Leftrightarrow\orbr{\begin{cases}x-20=-10\\x-20=10\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=10\\x=30\end{cases}}\)
Vậy \(x\in\left\{10;30\right\}\)
a)\(\left(3x-1\right)⋮\left(x-1\right)\)
\(\Leftrightarrow\left(3x-3+2\right)⋮\left(x-1\right)\)
Vì \(\left(3x-3\right)⋮\left(x-1\right)\)nên \(2⋮\left(x-1\right)\)
\(\Rightarrow x-1\inƯ\left(2\right)=\left\{\pm1;\pm2\right\}\)
Lập bảng :
| \(x-1\) | \(-2\) | \(-1\) | \(1\) | \(2\) |
| \(x\) | \(-1\) | \(0\) | \(2\) | \(3\) |
Vậy \(x\in\left\{-1;0;2;3\right\}\)
b)\(\left(x-5\right)\left(y+1\right)=5\)
\(\Leftrightarrow\hept{\begin{cases}x-5\\y+1\end{cases}}\inƯ\left(5\right)=\left\{\pm1;\pm5\right\}\)
Lập bảng :
| \(x-5\) | \(-5\) | \(-1\) | \(1\) | \(5\) |
| \(y+1\) | \(-1\) | \(-5\) | \(5\) | \(1\) |
| \(y\) | \(0\) | \(4\) | \(6\) | \(10\) |
| \(x\) | \(-2\) | \(-6\) | \(4\) | \(0\) |
Vậy \(x,y\in\left\{\left(0,-2\right);\left(4,-6\right);\left(6,4\right);\left(10,0\right)\right\}\)
ít một thoi.
Bài 1.
\(a,-2011-\left(200-2011\right)\)
\(=-2011+2011-200\)
\(=-200\)
\(b,\left(-2\right)^2-\left(-2000\right)^0+\left(-1\right)^{2018}-\left|-20\right|\)
\(=4-1+1-20\)
\(=-16\)
\(c,23\cdot18-23\cdot26+\left(-23\right)\cdot2\)
\(=23\left(18-26-2\right)\)
\(=-230\)
