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1. Ta có: \(3xy\left(a^2+b^2\right)+ab\left(x^2-9y^2\right)\)
\(=3xya^2+3xyb^2+abx^2+ab9y^2\)
\(=\left(3xya^2+abx^2\right)+\left(3xyb^2+ab9y^2\right)\)
\(=ax\left(3ya+bx\right)+3by\left(xb+3ya\right)\)
\(=\left(3ya+xb\right)\left(3yb+ax\right)\)
2.Check lại đề hộ mình nha:((
Câu 2 nên sủa lại đề nha
2. xy(a2+2b2)+ab(2x2+y2)
=xya2+xy2b2+ab2x2+aby2
=(xya2+aby2)+(xy2b2+ab2x2)
=ay(ax+by)+2bx(by+ax)
=(ax+by(ay+2bx)
a) \(x^7+x^5+1\)
\(=x^7+x^6+x^5-x^6-x^5-x^4+x^5+x^4+x^3-x^3-x^2-x+x^2+x+1\)
\(=x^5\left(x^2+x+1\right)-x^4\left(x^2+x+1\right)+x^3\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\)
\(=\left(x^2+x+1\right)\left(x^5-x^4+x^3-x+1\right)\)
b) \(x^8+x^4+1\)
\(=x^8-x^6+x^4+x^6-x^4+x^2+x^4-x^2+1\)
\(=x^4\left(x^4-x^2+1\right)+x^2\left(x^4-x^2+1\right)+\left(x^4-x^2+1\right)\)
\(=\left(x^4+x^2+1\right)\left(x^4-x^2+1\right)\)
\(=\left(x^4+x^3+x^2-x^3-x^2-x+x^2+x+1\right)\left(x^4-x^2+1\right)\)
\(=\left[x^2\left(x^2+x+1\right)-x\left(x^2+x+1\right)+\left(x^2+x+1\right)\right]\left(x^4-x^2+1\right)\)
\(=\left(x^2-x+1\right)\left(x^2+x+1\right)\left(x^4-x^2+1\right)\)
A/ \(2x^2+7x+5=2\left(x^2+2x+1\right)+3x+3=2\left(x+1\right)^2+3\left(x+1\right)\)
\(=\left(x+1\right)\left(2x+5\right)\)
B/ \(x^2-4x-5=\left(x^2-4x+4\right)-9=\left(x-2\right)^2-3^2=\left(x-5\right)\left(x+1\right)\)
C/ \(x^4+x^3+x+1=x^3\left(x+1\right)+\left(x+1\right)=\left(x+1\right)\left(x^3+1\right)=\left(x+1\right)^2\left(x^2-x+1\right)\)
D/\(x^4+4x^2-5=\left(x^4+4x^2+4\right)-9=\left(x^2+2\right)^2-3^2=\left(x^2-1\right)\left(x^2+5\right)=\left(x-1\right)\left(x+1\right)\left(x^2+5\right)\)
a) = 2x^2 + 2x +5x + 5 = 2x(x+1) + 5(x+1) = (2x+5)(x+1)
b) = x^2 + x - 5x - 5 = x(x-1) - 5(x-1) = (x-5)(x-1)
c) = x^3 ( x+1) + x+1 = (x^3+1) (x+1) = (x+1)^2 * (x^2 - x +1)
d) = x^4 - x^2 + 5x^2 -5 = x^2 (x^2-1) + 5(x^2-1) = (x^2+5)(x-1)(x+1)
a/ \(E=a^6+a^4+a^2b^2+b^4-b^6\)
\(E=\left[\left(a^2\right)^2+2a^2b^2+\left(b^2\right)^2\right]+\left(a^6-b^6\right)-a^2b^2\)
\(E=\left[\left(a^2+b^2\right)^2-\left(ab\right)^2\right]+\left(a^3-b^3\right)\left(a^3+b^3\right)\)
\(E=\left(a^2-ab+b^2\right)\left(a^2+ab+b^2\right)+\left(a-b\right)\left(a^2+ab+b^2\right)\left(a+b\right)\left(a^2-ab+b^2\right)\)
\(E=\left(a^2-ab+b^2\right)\left(a^2+ab+b^2\right)\left[1+\left(a-b\right)\left(a+b\right)\right]\)
\(E=\left(a^2-ab+b^2\right)\left(a^2+ab+b^2\right)\left(1+a^2-b^2\right)\)
\(a^6+a^4+a^2b^2+b^4-b^6\)
\(a^2\left(a^4+a^2b^2+b^4\right)-b^2\left(a^4+a^2b^2+b^4\right)+\left(a^4+a^2b^2+b^4\right)\)
\(=\left(a^4+a^2b^2+b^4\right)\left(a^2-b^2+1\right)\)
\(=\left(a^2+b^2+ab\right)\left(a^2+b^2-ab\right)\left(a^2-b^2+1\right)\)
A/ \(16x-5x^2-3=\left(15x-3\right)-\left(5x^2-x\right)=3\left(5x-1\right)-x\left(5x-1\right)=\left(5x-1\right)\left(3-x\right)\)
B/ \(x^3-3x^2+1-3x=\left(x^3-4x^2+x\right)+\left(x^2-4x+1\right)=x\left(x^2-4x+1\right)+\left(x^2-4x+1\right)\)
\(=\left(x+1\right)\left(x^2-4x+1\right)\)
C/ \(x^3-3x^2-4x+12=x^2\left(x-3\right)-4\left(x-3\right)=\left(x-3\right)\left(x-2\right)\left(x+2\right)\)
D/ \(\left(2x+1\right)^2-\left(x-1\right)^2=\left(2x+1-x+1\right)\left(2x+1+x-1\right)=3x\left(x+2\right)\)
\(x^3-x^2-4\)
\(=x^3-2x^2+x^2-4\)
\(=\left(x^3-2x^2\right)+\left(x^2-4\right)\)
\(=x^2\left(x-2\right)+\left(x-2\right)\left(x+2\right)\)
\(=\left(x^2+x+2\right)\left(x-2\right)\)
Đề đúng :
\(x^3-5x^2+8x-4\)
\(=x^3-x^2-4x^2+4x+4x-4\)
\(=\left(x^3-x^2\right)-\left(4x^2-4x\right)+\left(4x-4\right)\)
\(=x^2\left(x-1\right)-4x\left(x-1\right)+4\left(x-1\right)\)
\(=\left(x^2-4x+4\right)\left(x-1\right)\)
\(=\left(x^2-2.2.x+2^2\right)\left(x-1\right)\)
\(=\left(x-2\right)^2\left(x-1\right)\)
a) 4(x2-y2)-8(x-ay)-4(a2-1)
=> 4x2-4y2-8x+8ay-4a2+4
=> 4(x2-y2-2x+2ay-a2+1)
c) a5+a4+a3 +a2 +a+1
=> a(a4+a3+a2+a+1)+1
x2+x- y2+y
=x2-y2+ x+y
=(x-y)(x+y)+(x+y)
=(x-y+1)(x+y)
h nhé
cảm ơn
x2+x-y2+y
=x2-y2+x+y
=(x-y)(x+y)+(x+y)
=(x+y)(x-y+1)