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NL
0
NP
4
30 tháng 10 2020
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)
EH
21 tháng 10 2017
3x^2 +3y^2 -6xy -12
=3(x^2 - 2xy +y^2 - 2^2 )
=3 (x-y)^2 - 2^2
=3(x-y-2)(x-y+2)
3(x+y) -(x^2+2xy+y^2)
=3(x+y) -(x+y)^2
(x+y)(3-x-y)
BT
2
YN
19 tháng 10 2021
1) \(\left(x^2+8x+7\right).\left(x+3\right).\left(x+5\right)+15\)
\(=\left(x^2+8x+7\right).\left(x^2+5x+3x+15\right)+15\)
\(=\left(x^2+8x+7\right).\left(x^2+8x+15\right)+15\)
Ta đặt: \(x^2+8x+7=n\)
\(=n.\left(n+8\right)+15\)
\(=n^2+8n+15\)
\(=n^2+3n+5n+15\)
\(=\left(n^2+3n\right)+\left(5n+15\right)\)
\(=n.\left(n+3\right)+5.\left(n+3\right)\)
\(=\left(n+3\right).\left(n+5\right)\)
\(=\left(x^2+8x+7+3\right).\left(x^2+8x+7+5\right)\)
\(=\left(x^2+8x+10\right).\left(x^2+8x+12\right)\)
\(=\left(x^2+8x+10\right).\left(x^2+2x+6x+12\right)\)
\(=\left(x^2+8x+10\right).[x.\left(x+2\right)+6.\left(x+2\right)]\)
\(=\left(x^2+8x+10\right).\left(x+2\right).\left(x+6\right)\)
YN
19 tháng 10 2021
2) \(x^2-2xy+3x-3y-10+y^2\)
\(=\left(x-y\right)^2+3.\left(x-y\right)-10\)
Ta đặt: \(x-y=n\)
\(=n^2+3n-10\)
\(=n^2-2n+5n-10\)
\(=\left(n^2-2n\right)+\left(5n-10\right)\)
\(=n.\left(n-2\right)+5.\left(n-2\right)\)
\(=\left(n-2\right).\left(n+5\right)\)
\(=\left(x-y-2\right).\left(x-y+5\right)\)
TN
2
BO
20 tháng 10 2019
3x2-3y2-2(x-y)2
=3(x2-y2)-2(x-y)2
=3(x-y)(x+y)-2(x-y)(x-y)
=(x-y)(3x+3y-x+y)
=(x-y)(2x+4y)
=2(x-y)(x+2y)
20 tháng 5 2018
a) x2 + 6x + 9 = x2 + 2 . x . 3 + 32 = (x + 3)2
b) 10x – 25 – x2 = -(-10x + 25 +x2) = -(25 – 10x + x2)
= -(52 – 2 . 5 . x – x2) = -(5 – x)2
c) 8x3 - 1/8 = (2x)3 – (1/2)3 = (2x - 1/2)[(2x)2 + 2x . 12 + (1/2)2]
= (2x - 1/2)(4x2 + x + 1/4)
d)1/25x2 – 64y2 = (1/5x)2(1/5x)2- (8y)2 = (1/5x + 8y)(1/5x - 8y)
M
2 tháng 7 2016
1) \(x^3-x+y^3-y\)
\(=\left(x^3+y^3\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2-xy+y^2\right)-\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2-xy+y^2-1\right)\)
2)\(3x^2+6xy+3y^2-3z^2=3\left(x^2+2xy+y^2-z^2\right)\)
\(=3\left[\left(x+y\right)^2-z^2\right]=3\left(x+y-x\right)\left(x+y+z\right)\)
3)\(x^3+y^3-3x-3y=\left(x+y\right)\left(x^2-xy+y^2\right)-3\left(x+y\right)\)
\(=\left(x+y\right)\left(x^2-xy+y^2-3\right)\)
2 tháng 7 2016
\(1.x^3+y^3-x-y=\left(x+y\right)\left(x^2-xy+y^2\right)-\left(x+y\right)=\left(x+y\right)\left(x^2-xy+y^2-1\right)\)
2.\(3\left(x^2+6xy+y^2-z^2\right)=3\left[\left(x+y\right)^2-z^2\right]=3\left(x+y+z\right)\left(x+y-z\right)\)
3.\(\left(x+y\right)\left(x^2-xy+y^2\right)-3\left(x+y\right)=\left(x+y\right)\left(x^2-xy+y^2-3\right)\)
cho mình nha
CZ
2
10 tháng 8 2017
1)
x^2-y^2-2(x+y)=(x-y)(x+y)-2(x+y)
=(x+y)(x-y-2)
2)
3x^2-3y^2-2(x-y)^2=3(x-y)(x+y)-2(x-y)^2
=(x-y)(3x+3y-2(x-y))
=(x-y)(x+5y)
10 tháng 8 2017
1) \(x^2-y^2-2\left(x+y\right)\)
=\(\left(x-y\right)\left(x+y\right)-2\left(x+y\right)\)
=\(\left(x+y\right)\left(x-y-2\right)\)
2)\(3x^2-3y^2-2\left(x-y\right)^2\)
=\(3\left(x^2-y^2\right)-2\left(x-y\right)^2\)
=\(3\left(x-y\right)\left(x+y\right)-2\left(x-y\right)^2\)
=\(\left(x-y\right)\left(3\left(x+y\right)-2\left(x-y\right)\right)\)
=\(\left(x-y\right)\left(3x+3y-2x+2y\right)\)
=\(\left(x-y\right)\left(x+5y\right)\)
YF
1
28 tháng 5 2016
\(x^2-2xy+y^2+3x-3y-10=\left(x^2-2xy+y^2\right)+3\left(x-y\right)-10=\left(x-y\right)^2+3\left(x-y\right)-10=\left(x-y\right)^2-2\left(x-y\right)+5\left(x-y\right)-10=\left(x-y\right)\left(x-y-2\right)+5\left(x-y-2\right)=\left(x-y+5\right)\left(x-y-2\right)\)
28 tháng 5 2016
= ( x - y)^2 - 3 ( x - y) . -10
= ( x - y)^2 - 2.(x-y) . 3/2 +9/4 - 49/4
= ( x - y - 3/2) ^2 - (7/2)^2
= ( x- y - 3/2 - 7/2 )( x - y -3/2 + 7/2 )
=( x - y - 5 )( x - y + 2)
1.\(x\left(x+y\right)-3x-3y=x\left(x+y\right)-3\left(x+y\right)=\left(x-3\right)\left(x+y\right)\)
2.\(\left(3x+1\right)^2-\left(x-2\right)^2=\left(3x+1+x-2\right)\left(3x+1-x+2\right)=\left(4x-1\right)\left(2x+3\right)\)
a, \(x\left(x+y\right)-3x-3y=x\left(x+y\right)-3\left(x-y\right)=\left(x-3\right)\left(x-y\right)\)
b, \(\left(3x+1\right)^2-\left(x-2\right)^2=9x^2+6x+1-\left(x^2-4x+4\right)\)
\(=9x^2+6x+1-x^2+4x-4=8x^2+10x-3=\left(4x-1\right)\left(2x+3\right)\)