\(\left(\frac{1}{2}x+2y\right)^3\)=\(\left(\frac{1}{2}x\right)^3+3\cdot\left(\frac{1}{2}x\right)^2\cdot2y+3\cdot\frac{1}{2}x\cdot\left(2y\right)^2+\left(2y\right)^3\)
=\(\frac{1}{8}x^3+\frac{3}{2}x^2y+6xy^2+8y^3\)
\(\left(3x^2-2y\right)^3=\left(3x^2\right)^3-3\cdot\left(3x^2\right)^2\cdot2y+3\cdot3x^2\left(2y\right)^2-\left(2y\right)^3\)
\(=\)\(27x^6-54x^4y+36x^2y^2-8y^3\)
1, ( x+1/3)^3
2, ( 2x+y^2)^3
3, ( 1/2x^2+1/3y)^3
4, ( 3x^2-2y)^3
5, ( 2/3x^2-1/2y)^3
6, ( 2x+1/2)^3
7, ( x-3)^3
8, ( x+1).(X^2+3x+9)
9, ( x-3).( x^2+3x+9)
10, ( x-2).( x^2+2x+4)
11, ( x+4).( x^2-4x+16)
12, ( x-3y).( x^2+3xy+9y^2)
13, ( x^2-1/3). ( x^4+1/3x^2+1/9)
14, ( 1/3x+2y).( 1/9x^2-2/3xy+4y^2)
Đưa về HĐT
27x^3 - 27 x^2 +3x - 1
1/27 + x^3
x^3- 3x^2+3x-1
0,001-1000x^3
12/5 x^2y^2-9x^4 - 4/25y^4
a^2y^2+b^2x^2-2axby
100-(3x-y)^2
64x^2-(8a+b)^2
27x^3-a^3b^3
(x+2)^2-2x(x+1)+(x-3)(x+3)
(x+2y)(x^2-2xy+4y^2)-(x-2y)(x^2+2xy+4y^2)+2y^3
(3+x)(x^2-9)-(x-3)(x^2+3x+9)
(x-y)^3-(x-y)(x^2+xy+y^2)
Rút gọn:
A=(x^4 - 3x^2 + 9)(x^2 + 3) + (3 - x^2)^2
M= 5(x+2y)^2 - (3y + 2x)^2 + (4x - y)^2 + 3(x - 2y)(x + 2y)
E= (6x + 1)^2 + (6x - 1)^2 - 2(1 + 6x)(6x - 1)
C= (x^2 + 4)(x + 2)(x -2) - (x^2 - 3)^3
1/2.(6x-2y).(3x+y)
(2/3z-2/5x).(1/3z+1/5x).1/2
(5y-3x).1/4.(12x+20y)
(3/4y-1/2x).(x+3/2y).2
(a+b+c).(a+b-c)
(x-y+z).(x+y-z)
mng giúp mình vs ạ
Chứng minh đẳng thức sau:
a) (a + b + c) . (a - b + c) = a2 - b2 + c2 + 2ac
b) (3x + 2y) . (3x - 2y) - (4x - 2y) . (4x + 2y) = -7x2
c) (x - 1) . (x2 + x + 1) - (x +1) . (x2 - x +1) = -2
d) (2x + 1) . (4x2 - 2x + 1) - (2x - 1) . (4x2 +2x + 1) = 2
e) (x - 2y) . (x2 + 2xy + 4y2) - (2x - 1) . (x2 + 2xy + 4y2) = -16y3
1) Cho x + y = 5. Tính:
\(P=3x^2-2x+3y^2-2y+6xy-100\\ Q=x^3+y^3-2x^2-2y^2+3xy\left(x+y\right)-4xy+3\left(x+y\right)+10\)
Tính
a) (\(\frac{1}{3}x\) + 2y)(\(\frac{1}{9}x^{2^{ }}\)- \(\frac{2}{9}xy\) + 4y2)
b) (x2 - \(\frac{1}{3}\) )(x4 + \(\frac{1}{3}x^2\) + \(\frac{1}{9}\))
c) (x2 - 3y2 )(9y4 + x4 + 3x2y2)
d) (x3 + 2y3)(-2x3y3 + x6 + 4y6)
e) (-2x2 - 3y)(4x2 + 9y2 - 6x2y)
1.Khai triển các hằng đẳng thức sau ^^
a) (2x^3-y^2)^3
b) (x-3y)(x^2+3xy+9y^2)
c) ( x+2y+z) (x+2y-z)
d) (2x^3y -0,5x^2)^3
e) (x^2-3).(x^4+3x^2+9)
f) (2x-1)(4x^2+2x+1)
