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a)\(\left(x^2+4-4x\right)\left(x^2+4+4x\right)\)
b)\(x\left(y+1\right)+\left(y+1\right)=\left(y+1\right)\left(x+1\right)\)
c)\(\left(x+y\right)^2-2\left(x+y\right)=\left(x+y\right)\left(x+y-2\right)\)
a) x3 + 2x2y + xy2– 9x = x(x2 +2xy + y2 – 9)
= x[(x2 + 2xy + y2) – 9]
= x[(x + y)2 – 32]
= x(x + y – 3)(x + y + 3)
b) 2x – 2y – x2 + 2xy – y2 = (2x – 2y) – (x2 – 2xy + y2)
= 2(x – y) – (x – y)2
= (x – y)[2 – (x – y)]
= (x – y)(2 – x + y)
c) x4 – 2x2 = x2(x2 – (√2)2) = x2(x - √2)(x + √2).
\(=x^2+y^2+1-2x-2y+2xy-4\)
\(=\left(x+y-1\right)^2-2^2\)
\(=\left(x+y-3\right).\left(x+y+1\right)\)
Bài làm
a, x2 - 3x + xy - 3y
= x(x - 3) + y(x - 3)
= (x - 3)(x + y)
b, x2 + y2 - 2xy - 25
= (x2 - 2xy + y2) - 25
= (x + y)2 - 25
= (x + y + 5)(x + y - 5)
a) x2+ 4x+4-y2
=(x2+2.x.2+22)-y2
=(x+2)2-y2
=(x+2+y)(x+2-y)
b)(x2-2xy+y2)-z2
=(x-y)2-z2
=(x-y-z)(x-y+z)
\(x^2+4x+4-y^2\)
\(=\left(x^2+4x+4\right)-y^2\)
\(=\left(x+2\right)^2-y^2\)
\(=\left(x+2-y\right)\left(x+2+y\right)\)
hk tốt
^^
\(x^2+y^2-2x-2y+2xy-3\)
\(=x^2+y^2+1-2x-2y+2xy-4\)
\(=\left(x+y-1\right)^2-2^2\)
\(=\left(x+y-3\right).\left(x+y+1\right)\)
1) Ta có: 2xy - x2 - y2 + 16
= -(x2 - 2xy + y2 - 16)
= -[(x - y)2 - 16]
= -(x - y - 4)(x - y + 4)
2) x3 + 2x2y + xy2 - 9x
= x(x2 + 2xy + y2 - 9)
= x[(x + y)2 - 9]
= x(x + y - 3)(x + y + 3)
3) x4 - 2x2 = x2(x2 - 2)
1. 2xy-x2-y2+16= -(x2-2xy+y2-16) = -(x2-2xy+y2)-16 = -(x-y)2-16= (x+y)2-42= (x+y-4).(x+y+4)
2. x3+2x2y+xy2-9x= (có sai đề không vậy?)
(2xy+1)2-(2x+y)2
=(2xy+1-2x-y)(2xy+1+2x+y)
=[(2xy-y)-(2x-1)][(2xy+y)+(2x+1)]
=[y(2x-1)-(2x-1)][y(2x+1)+(2x+1)]
=(2x-1)(y-1)(2x+1)(y+1)