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TQ
3
M
22 tháng 12 2016
b)\(\left(9x^2-16y^2\right):\left(3x-4y\right)\)
=\(\left[\left(9x^2\right):\left(3x\right)\right]+\left[\left(-16y^2\right):\left(-4y\right)\right]\)
=\(3x+4y\)
15 tháng 10 2018
\(1.x^3+2x+x^2=x\left(x^2+x+2\right)\)
\(2.2x^3+4x^2+2x=2x\left(x^2+2x+1\right)=2x\left(x+1\right)^2\)
\(3.-3x^3-5x^2+8x=-3x^3+3x^2-8x^2+8x\)
\(=-3x^2\left(x-1\right)-8x\left(x-1\right)=\left(3x^2+8x\right)\left(1-x\right)\)
\(=x\left(3x+8\right)\left(1-x\right)\)
\(4.x^2+4x-5=x^2-x+5x-5=\left(x-1\right)\left(x+5\right)\)
\(5.6x^2-3x-3=6x^2-6x+3x-3=3\left(x-1\right)\left(2x+1\right)\)
\(6.3x^2-2x-5=3x^2+3x-5x-5=\left(x+1\right)\left(3x-5\right)\)
\(8.x^2-2x-4y^2-4y=\left(x-2y\right)\left(x+2y\right)-2\left(x+2y\right)\)\(=\left(x+2y\right)\left(x-y-2\right)\)
\(9.x^3+2x^2y+xy^2-9x=x\left(x^2+2xy+y^2-9\right)\)
\(=x\left(x+y-3\right)\left(x+y+3\right)\)
\(10.x^2-y^2+6x+9=\left(x+3-y\right)\left(x+3+y\right)\)
20 tháng 8 2020
a)( 6x - 2)2 ( 5x - 2)2 - 2( 6x - 2 )( 5x - 2 )
=(6x-2)2-2(6x-2)(5x-2)+(5x-2)2
=[(6x-2)-(5x-2)]2
=(6x-2-5x+2)2
=X2
b) ( x2 + 3x + 1)2 - 2( x2 + 3x + 1)( 3x + 1) + ( 9x2 - 6x + 1)
=( x2 + 3x + 1)2 - 2( x2 + 3x + 1)( 3x + 1)+[(3x)2-2.3x.1+12]
=( x2 + 3x + 1)2 - 2( x2 + 3x + 1)( 3x + 1)+(3x+1)2
=[( x2 + 3x + 1)-( 3x + 1)]2
=( x2 + 3x + 1- 3x - 1)2
=(x2)2
=x4
3 tháng 8 2016
\(9x^2-12xy+16y^2\)
\(=\left(3x\right)^2-2.\left(3x\right)\left(4y\right)+\left(4y\right)^2\)
\(=\left(3x-4y\right)^2\)
3 tháng 8 2016
\(P=\frac{x^2}{4}+x^2+1=\left(\frac{x}{2}\right)^2+2.x^2.\frac{1}{2}+1=\left(\frac{x}{2}+1\right)^2\)
2, a, \(9x^2-12x+9=\left(3x\right)^2-2.3.x.3+3^2=\left(3x-3\right)^2\ge0\)
25 tháng 7 2018
\(a.\left(2x-3\right)\left(4x^2+6x+9\right)-\left(2x+3\right)\left(4x^2-6x+9\right)\\ =\left(2x\right)^3-3^3-\left[\left(2x\right)^3+3^3\right]\\ =8x^3-9-\left(8x^3+9\right)\\ =8x^3-9-8x^3-9=-18\)
\(b.\left(x+1\right)\left(x^2-x+1\right)-\left(x-1\right)\left(x^2+x+1\right)\\ =x^3+1-\left(x^3-1\right)\\ =x^3+1-x^3+1=2\)
\(c.\left(3x-1\right)\left(3x+1\right)-\left(3x-2\right)^2\\ =9x^2-1-\left(9x^2-12x+4\right)\\ =9x^2-1-9x^2+12x-4\\ =12x-5\)
\(d.\left(2x-3\right)^2-\left(2x+3\right)\left(2x-3\right)\\ =\left(2x-3\right)\cdot\left[\left(2x-3\right)-\left(2x+3\right)\right]\\ =\left(2x-3\right)\cdot\left(2x-3-2x-3\right)\\ =\left(2x-3\right)\cdot\left(-6\right)\\ =-12x\cdot18\)
\(e.\left(3x-4\right)^2-\left(2x+4\right)^2\\ =9x^2-24x+16-\left(4x^2+16x+16\right)\\ =9x^2-24x+16-4x^2-16x-16\\ =5x^2-40x\)
\(f.\left(3x-5\right)^3-\left(3x+5\right)^3\\ =27x^3-135x^2+225x-125-\left(27x^3+135x^2+225x+125\right)\\ =27x^3-135x^2+225x-125-27x^3-135x^2-225x-125\\ =-270x^2-250\)
\(g.\left(2x-1\right)^2-\left(3x-1\right)^2\\ =4x^2-4x+1-\left(9x^2-6x+1\right)\\ =4x^2-4x+1-9x^2+6x-1\\ =-5x^2+2x\)
\(h.\left(x-2y\right)\left(x^2+2xy+4y^2\right)+\left(x^3-6y^3\right)\\ =x^3-8y^3+x^3-6y^3\\ =2x^3-14y^3\)
YN
10 tháng 10 2021
\(a)\) \(3x^2-6x=3x\left(x-2\right)\)
\(b)\) \(9x^3-9x^2y-4x+4y\)
\(=9x^2.\left(x-y\right)-4\left(x-y\right)\)
\(=\left(9x^2-4\right)\left(x-y\right)\)
\(=[\left(3x\right)^2-2^2]\left(x-y\right)\)
\(=\left(3x-2\right)\left(3x+2\right)\left(x-y\right)\)
\(c)\) \(x^3-2x^2-8x\)
\(=x\left(x^2-2x-8\right)\)
\(=x\left(x+2\right)\left(x-4\right)\)
Tính:
a) (2x + 3)3 = (2x)3 + 3.(2x)2.3 + 3.2x.32 + 33 = 8x3 + 36x2 + 54x + 27
b) (2x - 3)(4x2 + 6x + 9) = (2x - 3)[(2x)2 + 2x.3 + 32] = (2x)3 - 33 = 8x3 - 27
c) (3x + 4y)(9x2 - 12xy + 16y2) = (3x + 4y)[(3x)2 - 3x.4y + (4y)2] = (3x)3 + (4y)3 = 27x3 + 64y3.
a. (2x+3)3 = (2x)3+3.(2x)2.3+3.2x.32+33=8x +36x2+54x2+9=8x+90x2+9
b. (2x-3) (4x2+6x+9) = 2x.4x2+2x.6x+2x.9-3.4x2-3.6x-3.9 = 8x3+12x2+18x-12x2-18x-27 = 8x3-27
c. (3x+4y) (9x2-12xy+16y2) = 3x.9x2-3x.12xy+3x.16y2+4y.9x2-4y.12xy+4y.16y2= 27x3-36x2y+48xy2+36x2y-48xy2+64y3