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\(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\left(x^{3n}+y^{3n}\right)\)
\(=\left(x^{3n}-y^{3n}\right)\left(x^{3n}+y^{3n}\right)\)
\(=x^{6n}-y^{6n}\)
thanks CTV Ace Legona...nhưng CTV có thể trả lwoif giúp mình mấy câu hỏi nữa được không
Bài làm :
\(a,\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)
\(=8x+16-5x^2-10x+\left(4x-8\right)\left(x+1\right)+2\left(x^2-2^2\right)+10\)
\(=8x+16-5x^2-10x+4x^2+4x-8x-8+2x^2-8+10\)
\(=\left(8x-10x+4x-8x\right)+\left(-5x^2+4x^2+2x^2\right)+\left(16-8-8+10\right)\)
\(=-6x+x^2+10\)
a)\(\left(8-5x\right)\left(x+2\right)+4\left(x-2\right)\left(x+1\right)+2\left(x-2\right)\left(x+2\right)+10\)\(=8x+16-5x^2-2+4x-8x-8+2x-4x-4+10\)\(=\left(8x+4x-8x+2x-4x\right)+\left(16-2-8-4+10\right)+5x^2\)
\(=2x+12+5x^2\)
b)\(4\left(x-1\right)\left(x+5\right)-\left(x+2\right)\left(x+5\right)-3\left(x-1\right)\left(x+2\right)\)
\(=4x-4x-20-\left[x^2+5x+2x+10\right]-3\left[x^2+2x-1x-2\right]\)
\(=4x-4x-20-x^2-5x-2x-10-3x^2-6x+3x+6\)
\(=\left(4x-4x-5x-2x-6x+3x\right)+\left(-20-10+6\right)+\left(-x^2-3x^2\right)\)
\(=-10x-24-4x^2\)
c)\(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\left(x^{3n}+y^{3n}\right)\)
Xét tích \(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\Leftrightarrow\left(x^n\right)^3-\left(y^n\right)^3=x^{3n}-y^{3n}\)
Thay vào bt đã cho ta có \(\left(x^{3n}-y^{3n}\right)\left(x^{3n}+y^{3n}\right)\)
\(\Leftrightarrow\left(x^{3n}\right)^2-\left(y^{3n}\right)^2=x^{6n}-y^{6n}\)
a: \(4x^2\left(3x^{n+1}-2x^n\right)\)
\(=4x^2\cdot3x^{n+1}-4x^2\cdot2x^n\)
\(=12x^{n+3}-8x^{n+2}\)
b: \(2\left(x^{2n}+2x^ny^n+y^{2n}\right)-y^n\left(4x^n+2y^n\right)\)
\(=2x^{2n}+4x^ny^n+2y^{2n}-4x^ny^n-2y^{2n}\)
\(=2x^{2n}\)
c: \(=\left(x^{3n}-y^{3n}\right)\left(x^{3n}+y^{3n}\right)\)
\(=x^{6n}-y^{6n}\)
d: \(=4^n\cdot4-3\cdot4^n=4^n\)
a: 4x2(3xn+1−2xn)4x2(3xn+1−2xn)
=4x2⋅3xn+1−4x2⋅2xn=4x2⋅3xn+1−4x2⋅2xn
=12xn+3−8xn+2=12xn+3−8xn+2
b: 2(x2n+2xnyn+y2n)−yn(4xn+2yn)2(x2n+2xnyn+y2n)−yn(4xn+2yn)
=2x2n+4xnyn+2y2n−4xnyn−2y2n=2x2n+4xnyn+2y2n−4xnyn−2y2n
=2x2n=2x2n
c: =(x3n−y3n)(x3n+y3n)=(x3n−y3n)(x3n+y3n)
=x6n−y6n=x6n−y6n
d: =4n⋅4−3⋅4n=4n
\(\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^n-y^n\right)\left(x^{3n}+y^{3n}\right)\)
\(=\left(x^{2n}+x^ny^n+y^{2n}\right)\left(x^{4n}+x^ny^{3n}+x^{3n}y^n+y^{4n}\right)\)
\(=x^{2n}.\left(x^{4n}+x^ny^{3n}+x^{3n}y^n+y^{4n}\right)+x^ny^n.\left(x^{4n}+x^ny^{3n}+x^{3n}y^n+y^{4n}\right)+y^{2n}.\left(x^{4n}+x^ny^{3n}+x^{3n}y^n+y^{4n}\right)\)
\(=x^{6n}+x^{3n}y^{3n}+x^{5n}y^{4n}+x^{5n}y^n+x^{2n}y^{4n}+x^{4n}y^{2n}+x^ny^{5n}+x^{4n}y^{2n}+x^ny^{5n}+x^{3n}y^{3n}+y^{6n}\)
\(=x^{6n}+y^{6n}+x^{5n}y^{4n}+x^{5n}y^n+2x^{3n}y^{3n}+2x^{2n}y^{4n}+2x^ny^{5n}+2x^{4n}y^{2n}\)