Bài 1
a) \(x-2x+3x-4x+5x-6x\)
\(=x.\left(1-2+3-4+5-6\right)\)
\(=-3x\)
b) \(abc-3abc-2abc\)
\(=\left(1-3-2\right)abc\)
\(=-4abc\)
c) \(x^2+3x^2-4x^2-5x^2\)
\(=\left(1+3-4-5\right)x^2\)
\(=-5x^2\)
d) \(9\left(x+2\right)-8\left(x+2\right)+\left(x+2\right)\)
\(=\left(9-8+1\right)\left(x+2\right)\)
\(=2\left(x+2\right)\)
\(=2x+4\)
Bài 3
\(3\left(\left|1-x\right|-2\right)+1=7\)
\(3\left|1-x\right|-6+1=7\)
\(3\left|1-x\right|-5=7\)
\(3\left|1-x\right|=7+5\)
\(3\left|1-x\right|=12\)
\(\left|1-x\right|=\dfrac{12}{3}\)
\(\left|1-x\right|=4\)
*) \(x\le1\) ta có:
\(1-x=4\)
\(x=1-4\)
\(x=-3\) (nhận)
*) \(x>1\) ta có:
\(1-x=-4\)
\(x=1-\left(-4\right)\)
\(x=5\) (nhận)
Vậy \(x=-3;x=5\)
Bài 2
a) \(x\left(x-3\right)=0\)
\(\Rightarrow x=0;x-3=0\)
*) \(x-3=0\)
\(x=3\)
Vậy \(x=0;x=3\)
b) \(\left(x-2\right)\left(x+2\right)=0\)
\(\Rightarrow x-2=0;x+2=0\)
*) \(x-2=0\)
\(x=2\)
*) \(x+2=0\)
\(x=-2\)
Vậy \(x=-2;x=2\)
b) 32, 33, 34 , 35.
