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\(A=\left(5x-1\right)+2\left(1-5x\right)\left(4+5x\right)\left(5x+4\right)^2\)
\(=\left(5x-1\right)-2\left(5x-1\right)\left(5x+4\right)^3\)
\(=\left(5x-1\right)\left(1-2\left(5x+4\right)^3\right)\)
\(=\left(5x-1\right)\left(1-2\left(125x^3+300x^2+240x+64\right)\right)\)
\(=\left(5x-1\right)\left(1-250x^3-600x^2-480x-128\right)\)
\(=5x-1250x^4-3000x^3-2400x^2-640x-1+250x^3+600x^2+480x+128\)
\(=-1250x^4-2750x^3-1800x^2-110x+127\)
(Số hơi to)
\(B=\left(x-y\right)^3+\left(y+x\right)^3+\left(y-x\right)^3-3xy\left(x+y\right)\)
\(B=\left(x-y\right)^3+\left(y+x\right)^3-\left(x-y\right)^3-3xy\left(x+y\right)\)
\(B=\left(y+x\right)^3-3xy\left(x+y\right)\)
\(B=\left(x+y\right)\left[\left(x+y\right)^2-3xy\right]\)
\(B=\left(x+y\right)\left[x^2+2xy+y^2-3xy\right]\)
\(B=\left(x+y\right)\left(x^2-xy+y^2\right)\)
\(=x^3+y^3\)
P=x^3+3/5x^2y-3xy-3/5x^2y-xy+x^3
=2x^3-4xy
=2*(-2)^3-4*(-2)*1/3
=-16+8/3=-40/3
A = 5x(x - y) - y(5x - y)
A = 5x2 - 5xy - 5xy + y2
A = 5x2 - 10xy + y2 (1)
Thay x = -1; y = 3 vào (1), ta có:
5.(-1)2 - 10.(-1).3 + 32 = 44
B = 4y(x2 - 3xy + 3y2) - 2xy(2x - 6y - 3)
B = 4x2y - 12x2 + 12y3 - 4x2y + 12xy2 + 6xy
B = 12y3 + 6xy (1)
Thay x = 5; y = -1 vào (1), ta có:
12.(-1)3 + 6.5.(-1) = -42
C = 5x2(x - y2) + 3x(xy2 - y) - 5x3
C = 5x3 - 5x2y2 + 3x2y2 - 3xy - 5x3
C = -2x2y2 - 3xy (1)
Thay x = -2; y = -5 vào (1), ta có:
-2.(-2)2.(-5)2 - 3.(-2).(-5) = -230
D = 6x2(y2 - xy + 2x2y) - 3xy(2xy - x2 + 4x3)
D = 6x2y2 - 6x3y + 12x4y - 6x2y2 + 3x3y - 12x4y
D = -3x3y (1)
Thay x = 11; y = -1 vào (1), ta có:
-3.113.(-1) = 3993
a.
\(\left(x-y\right)\left(x^3+x^2y+xy^2+y^3\right)-x^4+y^4=x^4+x^3y+x^2y^2+xy^3-x^3y-x^2y^2-xy^3-y^4-x^4+y^4\)
\(=\left(x^4-x^4\right)+\left(y^4-y^4\right)+\left(x^3y-x^3y\right)+\left(xy^3-xy^3\right)+\left(x^2y^2-x^2y^2\right)=0\)
b.
\(\left(2-x\right)\left(1+2x\right)+\left(1+x\right)-\left(x^4+x^3-5x^2-5\right)=2+4x-x-2x^2+1+x-x^4-x^3+5x^2+5\)
\(=-x^4-x^3+\left(5x^2-2x^2\right)+\left(4x-x+x\right)+\left(1+2+5\right)=-x^4-x^3+3x^2+4x+8\)
c.
\(\left(x^2-7\right)\left(x+2\right)-\left(2x-1\right)\left(x-14\right)+x\left(x^2-2x-22\right)+35=x^3+2x^2-7x-14-2x^2+28x+x-14+x^3-2x^2-22x+35\)
\(=\left(x^3+x^3\right)+\left(2x^2-2x^2\right)+\left(28x-22x-7x+x\right)+\left(35-14\right)=2x^3+21\)
