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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:
\(10x^2\left(a-2b\right)^2-\left(x^2+2\right)\left(2b-a\right)^2\)
\(=-10x^2\left(2b-a\right)^2-\left(x^2+2\right)\left(2b-a\right)^2\)
\(=\left[-10x^2-\left(x^2+2\right)\right]\left(2b-a\right)^2\)
\(=\left(-10x^2-x^2-2\right)\left(2b-a\right)^2\)
\(=\left(-11x^2-2\right)\left(4b^2-4ab+a^2\right)\)
a) \(=x^2\left(a-b\right)-2\left(a-b\right)=\left(a-b\right)\left(x^2-2\right)\)
b) \(10x^2\left(a-2b\right)^2-\left(x^2+2\right)\left(a-2b\right)^2=\left(a-2b\right)^2\left(10x^2-x^2-2\right)=\left(a-2b\right)^2\left(9x^2-2\right)\)
c) \(50x^2\left(x-y\right)^2-8y^2\left(x-y\right)^2=\left(x-y\right)^2\left(50x^2-8y^2\right)\)
d) \(15a^mb.15^2-15a^mb.3=15^mb\left(15^2-3\right)=15^mb.222\)
\(a,4x^2yz-8xy^2z+12xyz^2\)
\(=4xyz\left(x-8y+12z\right)\)
\(b,y^2\left(a-b\right)+b-a\)
\(=y^2\left(a-b\right)+\left(b-a\right)\)
\(=y^2\left(a-b\right)-\left(a-b\right)\)
\(=\left(a-b\right)\left(y^2-1\right)\)
\(c,8m^2\left(m-n\right)+10\left(n-m\right)^2\)
\(=8m^2\left(m-n\right)+10\left(m-n\right)^2\)
\(=\left(m-n\right)\left(8m^2+10\left(m-n\right)\right)\)
\(d,3x\left(a-2b\right)^2-\left(x-2\right)\left(2b-a\right)^2\)
\(=3x\left(a-2b\right)^2-\left(x-2\right)\left(a-2b\right)^2\)
\(=\left(a-2b\right)^2\left(3x-x+2\right)\)
\(e,5a\left(x-y\right)^3-\left(a+4\right)\left(y-x\right)^3\)
\(=5a\left(x-y\right)^3-\left(a+4\right)\left(x-y\right)^3\)
\(=\left(x-y\right)^3\left(5a-a-4\right)\)
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)
a) x^2yz - x^3y^3z + xyz^2
=xyz(x-x2y2+z)
b) 4x^3 + 24x^2 - 12xy^2
= 4(x3+6x2-3xy2)
c) x^2( m + n) - 3y^2 (m + n)
=(m+5)(x2-3y2)
d) 4x^2(x - y) + 9y^2( y - x)
= 4x2(x-y)-9y2(x-y)
= (x-y)(4x2-9y2)
e) x^2(a - b) + 2( b - a)
= x2(a-b)-2(a-b)
= (a-b)(x2-2)
g) 50x^2(x - y)^2 - 8y^2(y - x)^2
= 50x2(x-y)2+8y2(x-y)2
= 2(x-y)2(25x2+4y2)
f)10x^2( a - 2b)^2 - (x^2 + 2)(2b - a)^2
= 10x2(a-2b)2+(x2-2)(a-2b)2
= (a-2b)2(10+x2-2)
= (a-2b)2(8+x2)
h) 15am+nb - 45amb( m thuộc N*)
= 15am.15anb - 45amb
= 15amb(15an-3)
Bài 1:
a) \(x^2-y^2+10x+25\)
\(=\left(x^2+10x+25\right)-y^2\)
\(=\left(x+5\right)^2-y^2\)
\(=\left(x+y+5\right)\left(x-y+5\right)\)
b) \(x^3-x^2-5x+125\)
\(=x^3+5x^2-6x^2-30x+25x+125\)
\(=x^2\left(x+5\right)-6x\left(x+5\right)+25\left(x+5\right)\)
\(=\left(x+5\right)\left(x^2-6x+25\right)\)
c) \(x^4+4y^4\)
\(=\left(x^2\right)^2+2x^22y^2+\left(2y^2\right)^2-2x^22y^2\)
\(=\left(x^2+2y^2\right)^2-\left(2xy\right)^2\)
\(=\left(x^2+2y^2-2xy\right)\left(x^2+2y^2+2xy\right)\)
d)Sửa đề \(a\left(b^2-c^2\right)+b\left(c^2-a^2\right)+c\left(a^2-b^2\right)\)
\(=a\left(b^2-c^2\right)-b\left[\left(b^2-c^2\right)+\left(a^2-b^2\right)\right]+c\left(a^2-b^2\right)\)
\(=a\left(b^2-c^2\right)-b\left(b^2-c^2\right)-b\left(a^2-b^2\right)+c\left(a^2-b^2\right)\)
\(=\left(a-b\right)\left(b^2-c^2\right)-\left(b-c\right)\left(a^2-b^2\right)\)
\(=\left(a-b\right)\left(b-c\right)\left(b+c\right)-\left(b-c\right)\left(a-b\right)\left(a+b\right)\)
\(=\left(a-b\right)\left(b-c\right)\left(b+c-a-b\right)\)
\(=\left(a-b\right)\left(b-c\right)\left(c-a\right)\)
e) \(7x^2-10xy+3y^2\)
\(=\left(\sqrt{7}x\right)^2-2.\sqrt{7}x.\sqrt{3}y+\left(\sqrt{3}y\right)^2\)
\(=\left(\sqrt{7}x-\sqrt{3}y\right)^2\)
f) Sửa đề \(a^3+b^3+c^3-3abc\)
\(=\left(a+b\right)^3+c^3-3ab\left(a+b\right)-3abc\)
\(=\left(a+b+c\right)\left[\left(a+b\right)^2-\left(a+b\right)c+c^2\right]-3ab\left(a+b+c\right)\)
\(=\left(a+b+c\right)\left(a^2+b^2+2ab-ac-bc+c^2\right)-3ab\left(a+b+c\right)\)
\(=\left(a+b+c\right)\left(a^2+b^2+c^2-ac-bc+2ab-3ab\right)\)
\(=\left(a+b+c\right)\left(a^2+b^2+c^2-ac-bc-ab\right)\)
h) \(xy\left(x+y\right)-yz\left(y+z\right)+xz\left(x-z\right)\)
\(=x^2y+xy^2-y^2z-yz^2+x^2z-xz^2\)
\(=\left(x^2y+x^2z\right)+\left(xy^2-xz^2\right)-yz\left(y+z\right)\)
\(=x^2\left(y+z\right)+x\left(y^2-z^2\right)-yz\left(y+z\right)\)
\(=x^2\left(y+z\right)+x\left(y+z\right)\left(y-z\right)-yz\left(y+z\right)\)
\(=\left(y+z\right)\left[x^2+x\left(y-z\right)-yz\right]\)
\(=\left(y+z\right)\left(x^2+xy-xz-yz\right)\)
\(=\left(y+z\right)\left[x\left(x+y\right)-z\left(x+y\right)\right]\)
\(=\left(y+z\right)\left(x+y\right)\left(x-z\right)\)
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)