Bài 1:
a: \(2xy\left(3x^2y-xy^2+y\right)\)
\(=2xy\cdot3x^2y-2xy\cdot xy^2+2xy\cdot y\)
\(=6x^3y^2-2x^2y^3+2xy^2\)
b: \(\left(6x^2-1\right)\left(6x^2+1\right)=\left(6x^2\right)^2-1=36x^4-1\)
c: \(-3x^2y\left(\frac12xy+\frac23y-\frac56xy^4\right)\)
\(=-3x^2y\cdot\frac12xy-3x^2y\cdot\frac23y+3x^2y\cdot\frac56xy^4\)
\(=-\frac32x^3y^2-2x^2y^2+\frac52x^3y^5\)
d: \(\left(xy-y\right)\left(xy-x\right)\)
\(=x^2y^2-x^2y-xy^2+xy\)
Bài 2:
a: \(4x^2+4x+1=\left(2x\right)^2+2\cdot2x\cdot1+1^2=\left(2x+1\right)^2\)
b: \(9x^2-24xy^2+16y^4=\left(3x\right)^2-2\cdot2x\cdot4y^2+\left(4y^2\right)^2\)
\(=\left(3x-4y^2\right)^2\)
c: \(x^2-2xy+y^2=\left(x-y\right)^2\)
d: \(x^3-6x^2+12x-8=\left(x-2\right)^3\)
Bài 3:
a: \(3x+\frac23=0\)
=>\(3x=-\frac23\)
=>\(x=-\frac23:3=-\frac29\)
b: \(x^2-2x+1=0\)
=>\(\left(x-1\right)^2=0\)
=>x-1=0
=>x=1
