4x(x2-2x+3)-3x(x+1)(x-2)+(2x-5)(x-7)-4x(x2-x+1)
=4x3-8x2+12x-3x(x2-2x+x-2)+2x2-14x-5x+35-4x3+4x2-4x
=4x3-8x2+12x-3x3+6x2-3x2+6x+2x2-14x-5x+35-4x3+4x2-4x
=-3x3+x2-5x+35
#H
4x(x2-2x+3)-3x(x+1)(x-2)+(2x-5)(x-7)-4x(x2-x+1)
=4x3-8x2+12x-3x(x2-2x+x-2)+2x2-14x-5x+35-4x3+4x2-4x
=4x3-8x2+12x-3x3+6x2-3x2+6x+2x2-14x-5x+35-4x3+4x2-4x
=-3x3+x2-5x+35
#H
Bài 1 Rút gọn biểu thức
a, [(3x - 2)(x + 1) - (2x + 5)(x2 - 1)] : (x + 1)
b, (2x + 1)2 - 2(2x + 1)(3 - x) + (3 - x)2
c, (x - 1)2 - (x + 1) (x2 - x + 1) - (3x + 1)(1 - 3x)
d, (x2 + 1)(x - 3) - (x - 3)(x2 + 3x + 9)
e, (3x +2)2 + (3x - 2)2 - 2(3x + 2)(3x - 2) + x
Bài 2 Phân tích các đa thức sau thành nhân tử
1, 3(x + 4) - x2 - 4x
2, x2 - xy + x - y
3, 4x2 -25 + (2x + 7)(5 - 2x)
4, x2 + 4x - y2 + 4
5, x3 - x2 - x + 1
6, x3 + x2y - 4x - 4y
7, x3 - 3x2 + 1 - 3x
8, 2x2 + 3x - 5
9, x2 - 7xy + 10y2
10, x3 - 2x2 + x - xy2
rút gọn A,B,C
A=(3x+7)(2x+3)-(3x-5)(2x+11)
B=(x2-2)(x2+x-1)-x(x3+x2-3x-2)
C=x(x3+x2-3x-2)-(x2-2)(x2+x-1)
Bài 1: Rút gọn
C) (x2 - 3) (x2 +3) - 5x2 (x + 1)2 - (x2 - 3x) ( x2 - 2x) + 4x (x + 2)2
D) -6x2 (x + 5)2 - ( x - 3)2 + (x2 - 2) (2x2 + 1) - 4x2 ( 3x - 4)2
1) Rút gọn C = ( 3x- 5) ( 2x + 11 ) - (2x + 3) ( 3x + 7)
2) Thực hiện phép tính ( 2x4+ 2x3 - 7x2 -x +3) : ( 2x2 - 1)
3) Tìm x : ( x+ 4) ( x2 - 4x + 16) - x ( x- 5) (x+ 5) = 264
tìm x:
a)3(2x-3)+2(2-x)=-3
b)2x(x2-2)+x2(1-2x)-x2=-12
c)3x(2x+3)-(2x+5)(3x-2)=8
d)4x(x - 1) - 3(x2-5)-x2=(x-3)-(x+4)
e)2(3x-1)(2x+5)-6(2x-1)(x+2)=-6
a)9x2 – 49 = 0
b)(x – 1)(x + 2) – x – 2 = 0
c)(4x + 1)(x - 2) - (2x -3)(2x + 1) = 7
d)x(3x + 2) + (x + 1)2 – (2x – 5)(2x + 5) = 0
e)(x + 3)(x2 – 3x + 9) –x(x – 1)(x + 1) – 27 = 0
f)(4x-3)^2-3x(3-4x)=0
Giải các phương trình sau:
a/ (3x – 2)(4x + 5) = 0
b/ (2,3x – 6,9)(0,1x + 2) = 0
c/ (4x + 2)(x2 + 1) = 0
d/(2x + 7)(x – 5)(5x + 1) = 0
e/ (x – 1)(2x + 7)(x2 + 2) = 0
f/ (3x + 2)(x2 – 1) = (9x2 – 4)(x + 1)
Giải các phương trình sau:
g/ x(x + 3)(x – 3) – (x + 2)(x2 – 2x + 4) = 0
h/ (3x – 1)(x2 + 2) = (3x – 1)(7x – 10)
i/ (x + 2)(3 – 4x) = x2 + 4x + 4
k/ x(2x – 7) – 4x + 14 = 0
m/ x2 + 6x – 16 = 0
n/ 2x2 + 5x – 3 = 0
Bài 1: Rút gọn các biểu thức:
a.(x + 2)2 - (x + 4)2 + x2 - 3x + 1
b.(2x + 2)2 - 4x(x + 2)
c. (2x - 1)2 - 2(2x - 3)2 + 4
d. (3x + 2)2 + 2(2 + 3x)(1 - 2y) + (2y - 1)2
e. (x2 + 2xy)2 + 2(x2 + 2xy)y2 + y4
f. (x - 1)3 + 3x(x - 1)2 + 3x2(x -1) + x3
g. (2x + 3y)(4x2 - 6xy + 9y2)
h. (x - y)(x2 + xy + y2) - (x + y)(x2 - xy + y2)
n. (x2 - 2y)(x4 + 2x2y + 4y2) - x3(x – y)(x2 + xy + y2) + 8y3