(14xy^2 + 21x^2y - 7x^3) : 7x
7x^2y-14xy^2+21x
2x(x-y)+3y(y-x)
6x(x-3)+2x-6
4x(x-y)^2+3x-3y
Chỉ mình gấp,mai mình nộp bài rồi.Cam on truoc
Chỉ theo cách học sinh lớp 8 nhé!
7x2y-14xy2+21x=7x(xy-2y2+3)=7xy(x-2y+3)
2x(x-y)+3y(y-x)=2x(x-y)-3y(x-y)=(2x+3y)(x-y)
6x(x-3)+2x-6=6x(x-3)+2(x-3)=(6x+2)(x-3)=2(x+1)(x-3)
4x(x-y)2+3x-3y=4x(x-y)2+3(x-y)=(4x2-y)(x-y)
c)x^4-4x^2y^2+y^2+2xy
d)7x^2-14xy^2+7y^4
e)2xy-15-6x+5y
g)9x^2-25y^2-6x+10
c: \(x^2-4x^2y^2+y^2+2xy\)
\(=\left(x+y\right)^2-\left(2xy\right)^2\)
\(=\left(x+y+2xy\right)\left(x+y-2xy\right)\)
d: \(7x^2-14xy^2+7y^4\)
\(=7\left(x^2-2xy^2+y^4\right)\)
\(=7\left(x-y^2\right)^2\)
ptđttnt : a, 9x^2y^3- 3x^4y^2- 6x^3y^2 + 18xy^4
b,7x^2y^2 - 21xy62z + 7xyz - 14xy
c,a^3x^2y - 5/2a63x^4 + 3/2a^4x^2y
7x^2 + 14xy - 4x - 8y
\(=7x\left(x+2y\right)-4\left(x+2y\right)=\left(7x-4\right)\left(x+2y\right)\)
phân tích đa tử
a,xy+3x-7y-21
b,2xy-15-6x+5y
2x^2y+2x^2y-x-y
d,7x^3y-3xyz-21x^2+9z
e, 4x^2 -2x -y^2-y
f, 9x^2-25y^2 -6x+10y
a
\(xy+3x-7y-21\\ =\left(xy+3x\right)-\left(7y+21\right)\\ =x\left(y+3\right)-7\left(y+3\right)\\ =\left(y+3\right)\left(x-7\right)\)
b
\(2xy-15-6x+5y\\ =\left(2xy-6x\right)-\left(15-5y\right)\\ =2x\left(y-3\right)-5\left(3-y\right)\\ =2x\left(y-3\right)+5\left(y-3\right)\\ =\left(y-3\right)\left(2x+5\right)\)
c Đề phải là \(\left(2x^2y+2xy^2-x-y\right)\) mới phân tích được: )
\(=2xy\left(x+y\right)-\left(x+y\right)\\ =\left(x+y\right)\left(2xy-1\right)\)
d
\(7x^3y-3xyz-21x^2+9z\\ =\left(7x^3y-21x^2\right)-\left(3xyz-9z\right)\\ =7x^2\left(xy-3\right)-3z\left(xy-3\right)\\ =\left(xy-3\right)\left(7x^2-3z\right)\)
e
\(4x^2-2x-y^2-y\\ =\left(2x\right)^2-y^2-\left(2x+y\right)\\ =\left(2x-y\right)\left(2x+y\right)-\left(2x+y\right)\\ =\left(2x+y\right)\left(2x-y-1\right)\)
f
\(9x^2-25y^2-6x+10y\\ =\left(3x\right)^2-\left(5y\right)^2-\left(6x-10y\right)\\ =\left(3x-5y\right)\left(3x+5y\right)-2\left(3x-5y\right)\\ =\left(3x-5y\right)\left(3x+5y-2\right)\)
a: =x(y+3)-7(y+3)
=(y+3)(x-7)
b: \(=2xy-6x+5y-15\)
=2x(y-3)+5(y-3)
=(y-3)(2x+5)
c: \(=2xy\left(x+y\right)-\left(x+y\right)=\left(x+y\right)\left(2xy-1\right)\)
d: \(=xy\left(7x^2-3z\right)-3\left(7x^2-3z\right)\)
=(7x^2-3z)(xy-3)
e: =4x^2-y^2-2x-y
=(2x-y)(2x+y)-(2x+y)
=(2x+y)(2x-y-1)
f: =(3x-5y)(3x+5y)-2(3x-5y)
=(3x-5y)(3x+5y-2)
7x^2-14xy^2-7y^4
7x2-14xy2+7y4=7(x2-2xy2+(y2)2) =7(x-y2)2
7x^2-14xy^2-7y^4
Nếu câu hỏi là phân tích đa thức thành nhân tử:
\(7x^2-14xy^2-7y^4=7\left(x^2-2xy^2-\left(y^2\right)^2\right)=7\left(x-y^2\right)^2\)
\(7x^2-14xy+7y^2\)
Phan h da thuc thanh nhan tu a ban ?
Ta co
7x2-14xy+7y2
=7(x2-2xy+y2)
=7(x-y)2
Ta có:\(7x^2-14xy+7y^2\)
\(=7\left(x^2-2xy+y^2\right)\)
\(=7\left(x^2-2.x.y+y^2\right)\)
\(=7\left(x-y\right)^2\)
1.Thực hiện phép tính. :
a) ( x + 2y )( x - 2y ) - 5 - x^2
2. Phân tích đa thức thành nhân tử :
a) 14x^3y^3 - 7x^2y + 21x^2y^5
b) 18x( 1 - x ) - 12y + 12xy
c) 9x^2 - y^2 + 1 - 6x
Bài 1: Thực hiện phép tính.
a) \(\left(x+2y\right)\left(x-2y\right)-5-x^2=x^2-4y^2-5-x^2=-4y^2-5\)
Bài 2: Phân tích đa thức thành nhân tử.
a) \(14x^3y^3-7x^2y+21x^2y^5=7x^2y\left(2xy^2-1+3y^4\right)\)
b) \(18x\left(1-x\right)-12y+12xy=18x\left(1-x\right)-12y\left(1-x\right)=6\left(1-x\right)\left(3x-2y\right)\)
c) \(9x^2-y^2+1-6x=\left(9x^2-6x+1\right)-y^2=\left(3x-1\right)^2-y^2=\left(3x-1-y\right)\left(3x-1+y\right)\)