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\(x^4+y^4+\left(x+y\right)^4\)
\(=x^4+y^4+\left(x^2+2xy+y^2\right)^2\)
\(=x^4+y^4+x^4+6x^2y^2+y^4+4x^3y+4xy^3\)
\(=2.\left(x^2+y^2\right)^2+4xy\left(x^2+y^2\right)+2x^2y^2\)
\(=2.\left(x^2+y^2\right)\left(x^2+y^2+2xy\right)+2x^2y^2\)
\(=2.\left[\left(x^2+y^2\right)\left(x+y\right)^2+x^2y^2\right]\)
Sai thì thôi nhé~
\(x^4+y^4+\left(x+y\right)^4\)
\(=x^4+y^4+x^4+4x^3y+6x^2y^2+4xy^3+y^4\)
\(=2x^4+4x^3y+6x^2y^2+4xy^3+2y^4\)
\(=2\left(x^4+2x^3y+3x^2y^2+2xy^3+y^4\right)\)
\(=2\left[\left(x^4+2x^3y+x^2y^2\right)+2\left(x^2+xy\right)y^2+y^4\right]\)
\(=2\left[\left(x^2+xy\right)^2+2\left(x^2+xy\right)y^2+\left(y^2\right)^2\right]\)
\(=2\left(x^2+xy+y^2\right)^2\)
Ta có : \(F=x^2-4^x+4-y^2\)
\(=\left(x^2-4^x+4\right)-y^2\)( nhóm hạng tử )
\(=\left(x-2\right)^2-y^2\)( đẳng thức số 2 )
\(=\left(x-2-y\right)\left(x-2+y\right)\)( đẳng thức số 3 )
Vậy : \(F=\left(x-2-y\right)\left(x-2+y\right)\)
x4 + 2x3 + x2 - y2
= ( x4 + 2x3 + x2 ) - y2
= [ ( x2 )2 + 2.x2.x + x2 ] - y2
= ( x2 + x )2 - y2
= ( x2 + x - y )( x2 + x + y )
\(=x^2\left(x^2+2x+1\right)-y^2\)
\(=x^2\left(x+1\right)^2-y^2\)
\(=x^2\left(x+1-y\right)\left(x+1+y\right)\)
x2 + 1 - y2 - 2x
= x2 - 2x + 1 - y2
=[x2 - 2x + 1] - y2
=[x-1]2 - y2
=[x-1-y][x-1+y]
a) \(x^2+1-y^2-2x=\left(x^2-2x+1\right)-y^2=\left(x-1\right)^2-y^2=\left(x-y-1\right)\left(x+y-1\right)\)
b) \(64x^4+y^4=\left(8x^2\right)^2+\left(y^2\right)^2=\left(8x^2\right)^2+16x^2y^2+\left(y^2\right)^2-16x^2y^2\)
\(=\left(8x^2+y^2\right)^2-\left(4xy\right)^2=\left(8x^2+y^2-4xy\right)\left(8x^2+y^2+4xy\right)\)
\(x^2+4x-y^2+4\)
\(=\left(x^2+2.x.2+2^2\right)-y^2\)
\(=\left(x+2\right)^2-y^2\)
\(=\left(x+2-y\right).\left(x+2+y\right)\)
Tham khảo nhé~
\(x^2+4x-y^2+4\)
\(=x^2+4x+4-y^2\)
\(=\left(x^2+4x+4\right)-y^2\)
\(=\left(x^2+2x.2+2^2\right)-y^2\)
\(=\left(x+2\right)^2-y^2\)
\(=\left[\left(x+2\right)+y^2\right].\left[\left(x+2\right)-y^2\right]\)
\(=\left(x+2+y^2\right)\left(x+3-y^2\right)\)
\(x^4+y^2-2x^2y+x^2+2x-2y\)
\(=\left(y^2-x^2y-xy\right)-\left(x^2y-x^4-x^3\right)+\left(xy-x^3-x^2\right)-\left(2y-2x^2-2x\right)\)
\(=y\left(y-x^2-x\right)-x^2\left(y-x^2-x\right)+x\left(y-x^2-x\right)-2\left(y-x^2-x\right)\)
\(=\left(y-x^2+x-2\right)\left(y-x^2-x\right)\)
\(x^4+y^4\)
= \(\left(x^2\right)^2+\left(y^2\right)^2+2x^2y^2-2x^2y^2\)
= \(\left(x^2+y^2\right)^2-2x^2y^2\)
= \(\left(x^2+y^2-\sqrt{2}xy\right)\left(x^2+y^2+\sqrt{2}xy\right)\)
Chúc bạn học tốt !!!
Bài làm
x4 + y4
= ( x2 )2 + 2x2y2 + ( y2 )2 - 2x2y2
= [ ( x2 )2 + 2x2y2 + ( y2 )2 ] - 2x2y2
= ( x2 + y2 )2 - 2x2y2
= ( x2 + y2 )2 - ( \(\sqrt{2}xy\))2
= ( x2 + y2 - \(\sqrt{2}xy\))( x2 + y2 + \(\sqrt{2}xy\))
# Học tốt #