a.(a+b)3 _ (a-b)3 _ 6a2b = a3 + 3a2b + 3ab2 + b3 _ (a3 _ 3a2b + 3ab2 _ b3) _ 6a2b
= a3 + 3a2b + 3ab2 + b3 _ a3 + 3a2b _ 3ab2 + b3 _ 6a2b
=2b3
b.(x-1)3_(x+1)3 + 6.(x-1)(x+1) = x3 _ 3x21 + 3x1 _ 13 _ ( x3 + 3x21 + 3x12 + 13) + 6(x2_12)
= x3 _ 3x21 + 3x1 _ 13 _ x3_ 3x21 _ 3x12 _ 13 + 6x2 _ 6.1
= 4x2 _ 8
Bài 1: Rút gọn
a)(x+9)(x-9)-x2
b)(10x-1)(10x+1)-(10x-1)2
c)(a+2b+3)(2a-2b-3)+(b-2c)2
d)(x-1)(x-2)-(x-2)(x+2)
Bài 1: Rút gọn
a) (x+3)^2+(x-3)^2+2(x^2-9)
b) (4x-1)^3-(4x-3)(16x^2+3)thu gọn
a) (x-1)^2-(x+2_.(x-2)
b)(2x+4).(8x-3).(4x+1)^2
c) (a+2)^3-a.(a-3)^2
Rút gọn
A=x(5x-3)-x^2(x-1)+x(x^2-62)-10+3x B=x(x^2+x+1)-x^2(x+1)-x+5
C=-3xy(-x+5y)+5y^2(3x-2y)+2(5y^2-3/2x^2y-2)
D=(3-x-6y)(x^2+2xy+4y^2)-3(x^3-8y^3+10)
Rút gọn
a) (x+1)(3-x)(x-2)2
b) 9x(1-x)+(3x-2)(3x+2)
Rút gọn
a)\(\dfrac{x}{x+1}+\dfrac{1}{x-1}-\dfrac{2x}{1-x^2}\)
b)\(\dfrac{x}{x-2}-\dfrac{4x}{x^2-4}-\dfrac{2}{x+2}\)
c)\(\dfrac{2x^2-3x-9}{x^2-9}-\dfrac{x}{x+3}-\dfrac{x+3}{3-x}\)
d)\(\dfrac{x+3}{x-2}+\dfrac{x+2}{1-x}-\dfrac{4x-x^2}{x^2-3x+2}\)
giúp mik vs
cảm ơn <3
Rút gọn
a) \((\dfrac{2x^2+3x}{x^3+1}+\dfrac{1}{x^2-x+1}).\dfrac{x^2-x+1}{x}\)
b) \(\left(\dfrac{1}{x-1}-\dfrac{1}{x}\right):\left(\dfrac{x+1}{x-2}-\dfrac{x+2}{x-1}\right)\)
c) \(\left(\dfrac{1}{x}+\dfrac{x}{x+1}\right).\dfrac{x^2+x}{x}\)
Bài1:Rút gọn
a,(4x-5)(3x+2)-(7-3x)(x+2)
b,(-2x+1)(x-5)-3(x-2)(x+1)
c,(x^2-7)(x-5)+(3x^2+5)(2x-4)
d,(x^2+3x-2)(x+4)-4x(x-5)
Bài2:Tìm xbiết
a,(x-4)(x+3)-(x+1)(x-5)=8
b,(3x-2)(x+1)-3x(x+7)=13
c,(x+5)(x-5)-x(x+2)=9
d,(x-1)(x^2+x+1)-x(x^2-3)=1
Rút gọn
a)(x-3)2-x.(x-6)
b)(2x+1)2-(3+2x).(2x-3)-4.(x+2)
c)(2x2-3x+1):(x-1)
Bài 1.Cho biểu thức
A = (\(\dfrac{2-x}{x+3}-\dfrac{3-x}{x+2}+\dfrac{2-x}{x^2+5x+6}\)) : (1-\(\dfrac{x}{x-1}\))
(a) Rút gọn A.
(b) Tìm x để A > 2.
Bài 2.Cho x+y=a,\(x^2+y^2=b\).Tính \(x^3+y^3\)theo a và b
