Câu 1:
a, (5x+1)(2x−y)
=10x²−5xy+2x−y
b, (2x+y)²
=4x²+4xy+y²
Câu 2:
a, 7(x−y)+x(x−y)
=(x−y)(7+x)
b, 2xy+3z+6y+xz
=2y(x+3)+z(x+3)
=(x+3)(2y+z
c, 3x²+6xy+3y²−3z²
=3[(x+y)²−z²]
=3(x+y−z).(x+y+z)
d, x²−7x+10
=x²−5x−2x+10
=(x−5)(x−2)
Câu 3:
a, 3x(x²−16)=0
⇔[x=0x²−16=0
⇔[x=0x=±4
b, (2x+3)²−(x−1)²=0
⇔(2x+3−x+1)(2x+3+x−1)=0
⇔(x+4).(3x+2)=0
⇔[x+4=03x+2=0
⇔[x=−4x=−2/3
c, 2x²−x−6=0
⇔2x²−4x+3x−6=0
⇔(x−2)(2x+3)=0
⇔[x=2x=−3/2
