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\(5x^2+10xy=5x\left(x+2y\right)\)
\(x^2+xy-3x-3y=x\left(x+y\right)-3\left(x+y\right)=\left(x-3\right)\left(x+y\right)\)
\(x^2+2x+1-y^2=\left(x+1\right)^2-y^2=\left(x+1-y\right)\left(x+1+y\right)\)
\(x^2-7x+6=x^2-x-6x+6=x\left(x-1\right)-6\left(x-1\right)=\left(x-1\right)\left(x-6\right)\)
1. b, \(x^2+xy+5-6x-y\)
\(=\left(x^2-6x+5\right)+\left(xy-y\right)\\ =\left(x-1\right)\left(x-5\right)+y\left(x-1\right)\\ =\left(x-1\right)\left(x+y-5\right)\)
1. a, \(x^2-y^2+3x^2z+6xyz+3y^2z\)
\(=\left(x^2-y^2\right)+\left(3x^2z+6xyz+3y^2z\right)\\ =\left(x-y\right)\left(x+y\right)+3z\left(x^2+2xy+y^2\right)\\ =\left(x-y\right)\left(x+y\right)+3z\left(x+y\right)^2\\ =\left(x+y\right)\left[x-y+3z\left(x+y\right)\right]\\ =\left(x+y\right)\left(x-y+3xz+3yz\right)\)
a) \(3y^2\left(2y-1\right)+y-y\left(1-y+y^2\right)-y^2+y \)
= \(6y^3-3y^2+y-y+y^2-y^3-y^2+y\)
= \(5y^3-3y^2+y\)
b)\(25x-4\left(3x-1\right)+\left(5-2x\right)7\)
= \(25x-12x+4+35-14x\)
= \(-x+39\)
c) \(11x-2\left(10x-1\right)-\left(4x-1\right)\left(-2\right)\)
= \(11x-\left(20x-2\right)-\left(-8x+2\right)\)
= \(11x-20x+2+8x-2\)
= \(-x\)
d) \(\left(\frac{1}{2x}\right)3-x\left(1-2x-\frac{1}{8x^2}\right)-x\left(x+\frac{1}{2}\right)\)
= \(\frac{3}{2x}-x+2x^2+\frac{x}{8x^2}-x^2-\frac{x}{2}\)
= \(\left(\frac{3}{2x}+\frac{1}{8x}-\frac{x}{2}\right)+x^2-x\)
= \(\left(\frac{12+1-4x^2}{8x}\right)+x^2-x\)
= \(\frac{13-4x^2}{8x}+\frac{8x^3}{8x}-\frac{8x^2}{8x}\)
= \(\frac{13-4x^2+8x^3-8x^2}{8x}\)
= \(\frac{8x^3-12x^2+13}{8x}\)
= x2 - \(\frac{3}{2}\)+\(\frac{13}{8x}\)
e) \(12\left(2-3x\right)+35x-\left(x+1\right)\left(-5\right)\)
= \(24-36x+35x-\left(-5x-5\right)\)
= \(24-36x+35x+5x+5\)
= 4x + 29
`@` `\text {Ans}`
`\downarrow`
`a,`
`A + B = 6xyz-3x^2-2 + 4xyz+3x^2-4`
`= (6xyz + 4xyz) + (-3x^2 + 3x^2) + (-2 - 4)`
`= 10xyz - 6`
____
`b,`
`A - B=6xyz-3x^2-2 - (4xyz+3x^2-4)`
`= 6xyz - 3x^2 - 2 - 4xyz - 3x^2 + 4`
`= (6xyz - 4xyz) + (-3x^2 - 3x^2) + (-2+4)`
`= 2xyz - 6x^2 + 2`
a: A+B
=6xyz-3x^2-2+4xyz+3x^2-4
=10xyz-6
b: A-B
=6xyz-3x^2-2-4xyz-3x^2+4
=-6x^2+2xyz+2
Bài 2:
a: \(A=\left(x+1\right)^3+5=20^3+5=8005\)
b: \(B=\left(x-1\right)^3+1=10^3+1=1001\)
a) Nhóm x^2 và y^2 ; x và y
b) Nhóm 3 hạng tử đầu lại vs nhau . Sau cùng xuất hiện nhân tử chung là 3
c) Nhóm 2 hạng tử đầu với nhau. ba hạng tử còn lại với nhau .
d) .....
D,ghép đầu với cuối là hằng dẳng thức 2 cái giữa với nhau là nhân tử chung là 3x
a) \(\left(3x^2y-11x^2-5y\right)\left(8xy-5x+6\right)\)
\(=3x^2y\left(8xy-5x+6\right)-11x^2\left(8xy-5x+6\right)-5y\left(8xy-5x+6\right)\)
\(=24x^3y^2-15x^3y+18x^2y-88x^3y+55x^3-66x^2-40xy^2+25xy-30y\)
\(=24x^3y^2-103x^3y+18x^2y+55x^3-66x^2-40xy^2+25xy-30y\)
b) \(\left(-4x^2y-5x^2+3y^3\right)\left(2x^2-xy+3y^2\right)\)
\(=-4x^2y\left(2x^2-xy+3y^2\right)-5x^2\left(2x^2-xy+3y^2\right)+3y^3\left(2x^2-xy+3y^2\right)\)
\(=-8x^4y+4x^3y^2-12x^2y^3-10x^4+5x^3y-15x^2y^2+6x^2y^3-3xy^4+9y^5\)
\(=-8x^4y+4x^3y^2-6x^2y^3-10x^4+5x^3y-15x^2y^2-3xy^4+9y^5\)
P/s: Ko chắc ạ!
Bài làm :
\(\text{a)}9\left(x+y-1\right)^2-4\left(2x+3y+1\right)^2\)
\(=\left(3x+3y-3\right)^2-\left(4x+6y+2\right)^2\)
\(=\left(3x+3y-3-4x-6y-2\right)\left(3x+3y-3+4x+6y+2\right)\)
\(=\left(-x-3y-5\right)\left(7x+9y-1\right)\)
\(\text{b)}3x^4y^2+3x^3y^2+3xy^2+3y^2\)
\(=\left(3x^4y^2+3xy^2\right)+\left(3x^3y^2+3y^2\right)\)
\(=3xy^2\left(x^3+1\right)+3y^2\left(x^3+1\right)\)
\(=\left(3xy^2+3y^2\right)\left(x^3+1\right)\)
\(=3y^2\left(x+1\right)\left(x+1\right)\left(x^2-x+1\right)\)
\(=3y^2\left(x+1\right)^2\left(x^2-x+1\right)\)
\(\text{c)}\left(x+y\right)^3-1-3xy\left(x+y-1\right)\)
\(=\left(x+y-1\right)\left[\left(x+y\right)^2+x+y+1\right]-3xy\left(x+y-1\right)\)
\(=\left(x+y-1\right)\left(x^2+2xy+y^2+x+y+1-3xy\right)\)
\(=\left(x+y-1\right)\left(x^2+x+y^2+y+1-xy\right)\)
\(d ) x^3+3x^2+3x+1-27z^3\)
\(=\left(x+1\right)^3-\left(3z\right)^3\)
\(=\left(x+1-3z\right)\left(x^2+2x+1+3xz+3z+9z^2\right)\)
các bn ơi
a, \(3x^2-6xyz+3y^2z=3\left(x^2-2xyz+y^2z\right)\)
b, \(x^2-3x-y^2+3y=x^2-y^2-3x+3y=\left(x-y\right)\left(x+y\right)-3\left(x-y\right)\)
\(=\left(x-y\right)\left(x+y+3\right)\)
c, \(3x^2-11x+6=3x^2-9x-2x+6x\)
\(=x\left(3x-2\right)-3\left(3x-2\right)=\left(x-3\right)\left(3x-2\right)\)