viết 8x3-27y3 dưới dạng tích
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A) \(x^3+27\)
\(=x^3+3^3\)
\(=\left(x+3\right)\left(x^2-3x+9\right)\)
B) \(x^3-\dfrac{1}{8}\)
\(=x^3-\left(\dfrac{1}{2}\right)^3\)
\(=\left(x-\dfrac{1}{2}\right)\left(x^2+\dfrac{1}{2}x+\dfrac{1}{4}\right)\)
C) \(8x^3+y^3\)
\(=\left(2x\right)^3+y^3\)
\(=\left(2x+y\right)\left(4x^2-2xy+y^2\right)\)
D) \(8x^3-27y^3\)
\(=\left(2x\right)^3-\left(3y\right)^3\)
\(=\left(2x-3y\right)\left(4x^2+6xy+9y^2\right)\)
a)\(\left(x+3\right)\left(x^2-3x+9\right)\)
b)\(\left(x-\dfrac{1}{2}\right)\left(x^2+\dfrac{1}{2}x+\dfrac{1}{4}\right)\)
c)\(\left(2x+y\right)\left(4x^2-2xy+y^2\right)\)
d)\(\left(2x-3y\right)\left(4x^2+6xy+9y^2\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(1-\dfrac{x^3}{8}=\left(1-\dfrac{1}{2}x\right)\left(1+\dfrac{1}{2}x+\dfrac{1}{4}x^2\right)\)
b: \(27x^3+1=\left(3x+1\right)\left(9x^2-3x+1\right)\)
c: \(64x^3-27y^3=\left(4x-3y\right)\left(16x^2+12xy+9y^2\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(8x^3-1=\left(2x-1\right)\left(4x^2+2x+1\right)\)
b: \(x^3+8y^3=\left(x+2y\right)\left(x^2-2xy+4y^2\right)\)
c: \(x^3+125=\left(x+5\right)\left(x^2-5x+25\right)\)
d: \(x^3-27y^3=\left(x-3y\right)\left(x^2+3xy+9y^2\right)\)
a) 8x3 - 1
= (2x)3 - 13
= (2x - 1)(4x2 + 2x + 1)
b) x3 + 8y3
= x3 + (2y)3
= (x + 2y)(x2 + 2xy + 4y2)
c) x3 + 125
= x3 + 53
= (x + 5)(x2 - 5x + 25)
d) x3 - 27y3
= x3 - (3y)3
= (x - 3y)(x2 + 3xy + 9y2)
Chúc bạn học tốt
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a, 2xy^2 ( x^3 -3xy - 4 )
b, x^2 - 4x - 4x +16
= x(x-4) - 4(x-4)
= (x-4) (x-4)
![](https://rs.olm.vn/images/avt/0.png?1311)
c: \(\dfrac{1}{8}x^3-\dfrac{9}{4}x^2y+\dfrac{27}{2}xy^2-27y^3=\left(\dfrac{1}{2}x-3y\right)^3\)
b: \(-x^3+12x^2-48x+64=\left(-x+4\right)^3\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a: x^3+8=(x+2)(x^2-2x+4)
b: =(3x+1)(9x^2-3x+1)
c: =(x+3)(x^2-3x+9)
d: =(4x-3y)(16x^2+24xy+9y^2)
\(a.x^3+8=\left(x+2\right)\left(x^2-2x+4\right)\)
\(b.27x^3+1=\left(3x+1\right)\left(9x-3x+1\right)\)
\(c.x^3+27=\left(x+3\right)\left(x^2-3x+9\right)\)
\(d.64x^3-27y^3=\left(4x-3y\right)\left(16x^2+12xy+9y^2\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có
8 x 3 – 12 x 2 y + 6 x y 2 – y 3 = ( 2 x ) 3 – 3 . ( 2 x ) 2 y + 3 . 2 x . y 2 – y 3 = ( 2 x – y ) 3
Đáp án cần chọn là: A
![](https://rs.olm.vn/images/avt/0.png?1311)
Ta có 8 x 3 + 36 x 2 + 54 x + 27 = ( 2 x ) 3 + 3 ( 2 x ) 2 . 3 + 3 . 2 x . 3 2 + 3 3 = ( 2 x + 3 ) 3
Đáp án cần chọn là: B
![](https://rs.olm.vn/images/avt/0.png?1311)
a)8x3 + * + * + 27y3 = (* + *)3
=>A=(2x+3y)^3
b) (2x+1)^3
c)(x-2y)^3
d)(3x-2)(3x+2)
e)(3x-1)(9x^2+3x+1)
f)....................
6: \(27x^3+1=\left(3x+1\right)\left(9x^2-3x+1\right)\)
7: \(\left(2x+1\right)^2=4x^2+4x+1\)
8: \(\left(2x-1\right)^2=4x^2-4x+1\)
9: \(9-16x^2=\left(3-4x\right)\left(3+4x\right)\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(a,=\left(x+1\right)^2\\ b,=\left(3x-y\right)^2\\ c,=\left(x-3\right)\left(x+3\right)\\ d,=\left(x+4\right)^3\\ e,=\left(x-2\right)^3\\ f,=\left(x+2\right)\left(x^2-2x+4\right)\\ g,=\left(2x-y\right)\left(4x^2+2xy+y^2\right)\)
\(8x^3-27y^3=\left(2x\right)^3-\left(3y\right)^3\)
\(=\left(2x-3y\right)\left(4x^2+6xy+9y^2\right)\)