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8 tháng 8 2023

\(A=\dfrac{1}{x^2+x}+\dfrac{1}{x^2+3x+2}+\dfrac{1}{x^2+5x+6}+\dfrac{1}{x+3}\) (ĐK: \(x\ne-1;x\ne0;x\ne-2;x\ne-3\))

\(A=\dfrac{1}{x\left(x+1\right)}+\dfrac{1}{\left(x+1\right)\left(x+2\right)}+\dfrac{1}{\left(x+2\right)\left(x+3\right)}+\dfrac{1}{x+3}\)

\(A=\dfrac{\left(x+2\right)\left(x+3\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}+\dfrac{x\left(x+3\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}+\dfrac{x\left(x+1\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}+\dfrac{x\left(x+1\right)\left(x+2\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)\(A=\dfrac{x^2+5x+6+x^2+3x+x^2+x+x^3+2x^2+x^2+2x}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{x^3+6x^2+11x+6}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{x^3+5x^2+6x+x^2+5x+6}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{x\left(x+5x+6\right)+\left(x^2+5x+6\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{\left(x^2+5x+6\right)\left(x+1\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{\left(x+1\right)\left(x+2\right)\left(x+3\right)}{x\left(x+1\right)\left(x+2\right)\left(x+3\right)}\)

\(A=\dfrac{1}{x}\)

c: Ta có: \(6x^2-\left(2x+5\right)\left(3x-2\right)\)

\(=6x^2-6x^2+4x-15x+10\)

=-11x+10

d: Ta có: \(2x\left(3x-1\right)-\left(x-3\right)\left(6x+2\right)\)

\(=6x^2-2x-6x^2-2x+18x+6\)

=14x+6

13 tháng 8 2021

(1𝑦/3+3)^3

(𝑦/3+3)^3

(𝑦/3+3⋅3/3)^3

(𝑦+3⋅3/3)^3

(𝑦+9/3)^3

\(\left(\dfrac{1}{3}y+3\right)^3=\dfrac{1}{27}y^3+y^2+9y+27\)

11 tháng 10 2023

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1 tháng 2 2017

-ab - ba

= -ab + (-ab)

= 2-ab (hai âm ab)

24 tháng 8 2018

-ab - ba

= -ab + (-ab) 

= -2ab

7 tháng 2 2016

=a3+2a2b+a2b+2ab2+ab2+b3

=(a3+2a2b+ab2)+(a2b+2ab2+b3)

=a(a2+2ab+b2)+b(a2+2ab+b2)

=(a+b)(a2+ab+ab+b2)

=(a+b)(a(a+b)+b(a+b))

=(a+b)(a+b)(a+b)=(a+b)3

7 tháng 2 2016

=a3 + 2a2 b+a2b+2ab2+ab3+b3

=(a3+2a2b+ab2)+(a2b+2ab2+b3)

=a(a2+2ab+b2)+b(a2+2ab+b3)

=(a+b)(a(a+b)+b(a-b)

=(a-b)(a+b)(a-b)=(a+b)2

\(\left(\dfrac{1}{3y+3}\right)^3=\dfrac{1}{\left(3y+3\right)^3}=\dfrac{1}{27y^3+81y^2+81y+27}\)

13 tháng 8 2021

\(\left(\dfrac{1}{3y+3}\right)^3=\dfrac{1^3}{\left(3y+3\right)^3}=\dfrac{1}{27\left(y^3+3y^2+3y+1\right)}\)

Bài 4: 

b: \(=x^2z\left(-1+3-7\right)=-5x^2z=-5\cdot\left(-1\right)^2\cdot\left(-2\right)=10\)

c: \(=xy^2\left(5+0.5-3\right)=2.5xy^2=2.5\cdot2\cdot1^2=5\)

6 tháng 12 2021

\(\text{ 2x.(x-2)+(x+3).(1-2x)}\\ =\left(2x^2-4x\right)+\left(x-2x^2+3-6x\right)\\ =2x\left(x-2\right)+\left(-5-2x^2+3\right)\)

7 tháng 11 2021

\(=8x^3-36x^2+54x-27+2x^2-8x^3-29=-34x^2+54x-56\)

\(=8x^3-36x^2+54x-27+2x^2-8x^3-29\)

\(=-34x^2+54x-56\)