b.
\(6x^2-12x+6=6\left(x^2-2x+1\right)\)
\(=6\left(x-1\right)^2\)
c.
\(4x^2-20x+25\)
\(=\left(2x-5\right)^2\)
d. Câu này đề sai
e.
\(x^5-x^3+x^2-1\)
\(=x^3\left(x^2-1\right)+x^2-1\)
\(=\left(x^2-1\right)\left(x^3+1\right)\)
\(=\left(x-1\right)\left(x+1\right)\left(x+1\right)\left(x^2-x+1\right)\)
\(=\left(x-1\right)\left(x+1\right)^2\left(x^2-x+1\right)\)
f.
\(x^2-2xy+y^2-9\)
\(=\left(x-y\right)^2-9\)
\(=\left(x-y+3\right)\left(x-y-3\right)\)
g.
Câu này giống hệt câu d, và ko phân tích được
h.
\(1-x^2+2xy-y^2\)
\(=1-\left(x^2-2xy+y^2\right)\)
\(=1-\left(x-y\right)^2\)
\(=\left(1-x+y\right)\left(1+x-y\right)\)
k.
\(4x^2-1+y^2-4xy\)
\(=\left(4x^2-4xy+y^2\right)-1\)
\(=\left(2x-y\right)^2-1\)
\(=\left(2x-y-1\right)\left(2x-y+1\right)\)
l.
\(-x^2-2xy-y^2+4\)
\(=4-\left(x^2+2xy+y^2\right)\)
\(=4-\left(x+y\right)^2\)
\(=\left(2+x+y\right)\left(2-x-y\right)\)
m.
\(3x^3+6x^2y+3xy^2\)
\(=3x\left(x^2+2xy+y^2\right)\)
\(=3x\left(x+y\right)^2\)
n.
\(20x^2+20xy+5y^2\)
\(=5\left(4x^2+4xy+y^2\right)\)
\(=5\left(2x+y\right)^2\)
o.
\(9a^4b^2-18a^3b^3+9a^2b^4\)
\(=9a^2b^2\left(a^2-2ab+b^2\right)\)
\(=9a^2b^2\left(a-b\right)^2\)
b) \(6x^2-12x+6=6\left(x^2-2x+1\right)=6\left(x-1\right)^2\)
c)\(4x^2-20x+25=\left(2x-5\right)^2\)
phần d bạn dung nhóm các hạng tử
phần e bạn dùng cch nhẩm nghiệm
p) \(2x-2y-x^2+2xy-y^2=2\left(x-y\right)-\left(x^2-2xy+y^2\right)=2\left(x-y\right)-\left(x-y\right)^2=\left(x-y\right)\left(2-\left(x-y\right)\right)=\left(x-y\right)\left(2-x+y\right)\)
p.
\(=2\left(x-y\right)-\left(x^2-2xy+y^2\right)\)
\(=2\left(x-y\right)-\left(x-y\right)^2\)
\(=\left(x-y\right)\left(2-x+y\right)\)
q.
\(25-\left(x^2-4xy+4y^2\right)\)
\(=25-\left(x-2y\right)^2\)
\(=\left(5-x+2y\right)\left(5+x-2y\right)\)