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a) x2yz - x3y3z + xyz2 = xyz.(x - x2y2 + z)
b) 4x3 + 24x2 - 12xy2 = 4x.(x2 + 6x - 3y2)
c) x2.(m+n) - 3y2.(m+n) = (m+n).(x2 - 3y2)
d) 4x2.(x-y) + 9y2.(y-x) = 4x2.(x-y) - 9y2.(x-y) = (x-y).(4x2 - 9y2)
e) x2.(a-b) + 2.(b-a) = x2.(a-b) - 2.(a-b) = (a-b).(x2 - 2)
f) 10x2.(a-2b)2 - (x2 + 2).(2b-a)2 = (a-2b)2.(10x2 - (x2 +2) ) = (a-2b)2.(9x2 - 2)
g) 50x2.(x-y)2 - 8y2.(y-x)2 = (x-y)2.2.(25x2 - 4y2)
h) 16am+2 - 45amb = 16am.a2 - 45amb = am.(16a2 - 45b)
a. 6x3y2 ( 2-x) + 9x2y2 (x-2)
= -6x3y2 (x-2) + 9x2y2 ( x-2)
= (x-2) 3x2y2 ( -2x + 3)
b. x2 - 4x + 4y - y2
= x2 - y2 - (4x - 4y )
= (x-y)(x+y) - 4( x-y)
= (x-y)(x+y-4)
c. 81x2 + 6yz -9y2-z2
= 81x2 - (9y2 - 6yz + z2 )
= (9x)2 - ( 3y - z )2
= (9x + 3y -z)(9x - 3y + z )
\(a,=6x^3y^2\left(2-x\right)-9x^2y^2\left(2-x\right)\)
\(=\left(2-x\right)\left(6x^3y^2-9x^2y^2\right)=\left(2-x\right)3x^2y^2\left(2x-3\right)\)
\(f,=\left(x-3-x-2\right)\left(x-3+x+2\right)\)
\(=-5\left(2x-1\right)\)
\(g,=\left(x-3\right)\left(x+3\right)+2\left(x+3\right)\)
\(=\left(x+3\right)\left(x-3+2\right)\)
\(=\left(x+3\right)\left(x-1\right)\)
a, 7x^3 + 5 ( x - y )^2 v- 7y^3
= 7 ( x^3 - y^3 ) + 5 ( x-y )^2
= 7 ( x - y )^3 + 5 ( x-y ) ^2
= [ 7 ( x- y ) + 5 ] ( x-y) ^2
c) \(x^2+x-ax-a\)
\(=x\left(x+1\right)-a\left(x+1\right)\)
\(=\left(x+1\right)\left(x-a\right)\)
d) \(2xy-ax+x^2-2ay\)
\(=2y\left(x-a\right)+x\left(x-a\right)\)
\(=\left(x-a\right)\left(2y+x\right)\)
e) \(x^2y+xy^2-x-y\)
\(=xy\left(x+y\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(xy-1\right)\)
f) \(25-10x-4y^2+x^2\)
\(=\left(x^2-10x+25\right)-\left(2y\right)^2\)
\(=\left(x-5\right)^2-\left(2y\right)^2\)
\(=\left(x-5-2y\right)\left(x-5+2y\right)\)
g) \(x^3-6xy+9y^2-36\)
h) \(4x^2-9y^2+4x-6y\)
\(=\left(2x\right)^2-\left(3y\right)^2+2\left(2x-3y\right)\)
\(=\left(2x-3y\right)\left(2x+3y\right)+2\left(2x-3y\right)\)
\(=\left(2x-3y\right)\left(2x+3y+2\right)\)
k) \(-x^2+5x+2xy-5y-y^2\)
\(=-\left(x^2-2xy+y^2\right)+5\left(x-y\right)\)
\(=-\left(x-y\right)^2+5\left(x-y\right)\)
\(=\left(x-y\right)\left(-x+y+5\right)\)
i) \(4x^2-25y^2-6x+15y\)
\(=\left(2x\right)^2-\left(5y\right)^2-3\left(2x-5y\right)\)
\(=\left(2x-5y\right)\left(2x+5y\right)-3\left(2x-5y\right)\)
\(=\left(2x-5y\right)\left(2x+5y-3\right)\)
a, \(x\left(y+z\right)^2+y\left(x+z\right)^2+z\left(x+y\right)^2+4xyz\)
\(=x\left(y+z\right)^2+x^2\left(y+z\right)+yz\left(y+z\right)\)
\(=\left(y+z\right)\left(xy+xz+z^2+yz\right)\)
\(=\left(y+z\right)\left[x\left(x+y\right)+z\left(x+y\right)\right]\)
\(=\left(y+z\right)\left(x+z\right)\left(x+y\right)\)
b, \(yz\left(y+z\right)+xz\left(z-x\right)-xy\left(x+y\right)\)
\(=yz\left(y+z\right)+xz^2-x^2z-x^2y-xy^2\)
\(=yz\left(y+z\right)-x\left(y+z\right)\left(y-z\right)-x^2\left(y+z\right)\)
\(=\left(y+z\right)\left(yz-xy+xz-x^2\right)\)
\(=\left(y+z\right)\left[y\left(z-x\right)+x\left(z-x\right)\right]\)
\(=\left(y+z\right)\left(y+x\right)\left(z-x\right)\)
f)\(\left(x-y\right)^2-4=\left(x-y-4\right)\left(x-y+4\right)\)
h) \(x^3+27=\left(x+3\right)\left(x^2-3x+9\right)\)
i)\(10x-x^2-25=-\left(x^2-10x+25\right)=-\left(x-5\right)^2\)
k)\(4x^2-12xy+9y^2=\left(2x\right)^2-2.2x.3y+\left(3y\right)^2=\left(2x-3y\right)^2\)
mấy bài này cơ bản mà, mở sgk toán 8 ra có các dạng đấy, đăng cũng đăng ít chứ, đăng nhiều quá
a)\(6x^3-9y^2=3\left(2x^3-3y^2\right)\)
b)\(4x^2y-8xy^2+18x^2y^2=2xy\left(2x-4y+9xy\right)\)
c)\(18x^2y-12x^3=6x^2\left(3y-2x\right)\)
d) \(5x\left(x-1\right)-3y\left(x-1\right)=\left(x-1\right)\left(5x-3y\right)\)
e)\(\left(x+1\right)^2-3\left(x+1\right)=\left(x+1\right)\left(x+1-3\right)=\left(x+1\right)\left(x-2\right)\)
g)\(\left(4x^2-4x+4\right)-\left(x+1\right)^2=\left(4x^2-4x+4\right)-\left(x^2+2x+1\right)\)
\(=4x^2-4x+4-x^2-2x-1\)\(=3x^2-6x+3\)\(=3\left(x^2-2x+1\right)\)
\(=3\left(x-1\right)^2\)
\(a,4x^2yz-8xy^2z+12xyz^2\)
\(=4xyz\left(x-8y+12z\right)\)
\(b,y^2\left(a-b\right)+b-a\)
\(=y^2\left(a-b\right)+\left(b-a\right)\)
\(=y^2\left(a-b\right)-\left(a-b\right)\)
\(=\left(a-b\right)\left(y^2-1\right)\)
\(c,8m^2\left(m-n\right)+10\left(n-m\right)^2\)
\(=8m^2\left(m-n\right)+10\left(m-n\right)^2\)
\(=\left(m-n\right)\left(8m^2+10\left(m-n\right)\right)\)
\(d,3x\left(a-2b\right)^2-\left(x-2\right)\left(2b-a\right)^2\)
\(=3x\left(a-2b\right)^2-\left(x-2\right)\left(a-2b\right)^2\)
\(=\left(a-2b\right)^2\left(3x-x+2\right)\)
\(e,5a\left(x-y\right)^3-\left(a+4\right)\left(y-x\right)^3\)
\(=5a\left(x-y\right)^3-\left(a+4\right)\left(x-y\right)^3\)
\(=\left(x-y\right)^3\left(5a-a-4\right)\)
học tốt nha
đúng gần hết nhưng bạn chưa khai triển hết, và câu cuối bạn làm không đúng:
a)=4xyz(x+(-2)y+3z)
b)=(a-b)(y-1)(y+1)
c)=2(m-n)(4m^2+5m-5m)
d)=2(a-b)^2.(x+1)
e)=2(x-y)^3.(3a+2)
Bạn khá hiểu bài rồi đó. Đúng hết 4 câu đầu luôn.
Bổ sung thêm vào câu 3 một chút (nối tiếp theo sau nhé):
\(\Rightarrow\left(m-n\right)\left(x-\sqrt{3}y\right)\left(x+\sqrt{3}y\right)\)
Bổ xung thêm vào câu 4:
\(\Rightarrow\left(x-y\right)\left(2x-3y\right)\left(2x+3y\right)\)
Sửa lại câu 5:
\(10x^2\left(a-2b\right)^2-\left(x^2+2\right)\left(2b-a\right)^2\)
\(=-10x^2\left(2b-a\right)^2-\left(x^2+2\right)\left(2b-a\right)^2\)
\(=\left[-10x^2-\left(x^2+2\right)\right]\left(2b-a\right)^2\)
\(=\left(-10x^2-x^2-2\right)\left(2b-a\right)^2\)
\(=\left(-11x^2-2\right)\left(4b^2-4ab+a^2\right)\)