bài 1:
a: \(=2x\left(x^2-4\right)=2x\left(x-2\right)\left(x+2\right)\)
b: \(=x\left(x-y\right)+\left(x-y\right)\left(x+y\right)=\left(x-y\right)\left(2x+y\right)\)
c: \(=\left(5x+25\right)^2-\left(3x+21\right)^2\)
\(=\left(5x+25-3x-21\right)\left(5x+25+3x+21\right)\)
\(=\left(2x+4\right)\left(8x+46\right)\)
\(=4\left(x+2\right)\left(2x+23\right)\)
Bài 2:
a: =>(x-1)(x-3)=0
=>x=1 hoặc x=3
b: =>(3x-5-x+1)(3x-5+x-1)=0
=>(4x-6)(2x-4)=0
=>x=2 hoặc x=3/2
c: =>(2-3x)(16-x^2)=0
hay \(x\in\left\{\dfrac{2}{3};4;-4\right\}\)
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