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10 tháng 9 2019

\(P:\frac{4x-2-16}{2x+1}=\frac{4x^2+4x+1}{x-2}\)

\(\Rightarrow P=\frac{4x^2+4x+1}{x-2}.\frac{4x^2-16}{2x+1}\)

\(\frac{\left(2x+1\right)^2}{x-2}.\frac{4.\left(x-2\right)\left(x+2\right)}{2x+1}\)

 \(\Rightarrow P=4.\left(2x+1\right).\left(x+2\right)\)

\(=4.\left(2x^2+x+4x+2\right)\)

\(8x^2+40x+8\)

Chúc bạn học tốt !!!

1: =(x+y-3x)(x+y+3x)

=(-2x+y)(4x+y)

2: =(3x-1-4)(3x-1+4)

=(3x+3)(3x-5)

=3(x+1)(3x-5)

3: =(2x)^2-(x^2+1)^2

=-[(x^2+1)^2-(2x)^2]

=-(x^2+1-2x)(x^2+1+2x)

=-(x-1)^2(x+1)^2

4: =(2x+1+x-1)(2x+1-x+1)

=3x(x+2)

5: =[(x+1)^2-(x-1)^2][(x+1)^2+(x-1)^2]

=(2x^2+2)*4x

=8x(x^2+1)

6: =(5x-5y)^2-(4x+4y)^2

=(5x-5y-4x-4y)(5x-5y+4x+4y)

=(x-9y)(9x-y)

7: =(x^2+xy+y^2+xy)(x^2+xy-y^2-xy)

=(x^2+2xy+y^2)(x^2-y^2)

=(x+y)^3*(x-y)

8: =(x^2+4y^2-20-4xy+16)(x^2+4y^2-20+4xy-16)

=[(x-2y)^2-4][(x+2y)^2-36]

=(x-2y-2)(x-2y+2)(x+2y-6)(x+2y+6)

30 tháng 10 2016

(x - 4)(x2 + 4x + 16) - x(x2 - 6) = 2

x3 - 64 - x3 + 6x = 2

6x = 2 + 64

6x = 66

x = 66 : 6

x = 11

x3 - 27 + 3x(x - 3)

= (x - 3)(x2 + 3x + 9) + 3x(x - 3)

= (x - 3)(x2 + 3x + 9 + 3x)

= (x - 3)(x2 + 6x + 9)

= (x - 3)(x + 3)2

5x3 - 7x2 + 10x - 14

= 5x(x2 + 2) - 7(x2 + 2)

= (x2 + 2)(5x - 7)

30 tháng 10 2016

mk cám ơn nhiều ạ

8 tháng 10 2019

ta có

\(5x=-3y=4z\)

\(\Rightarrow\frac{x}{12}=-\frac{y}{20}=\frac{z}{15}\)

\(\Rightarrow\frac{x}{12}=-\frac{y}{20}=\frac{3z}{45}=\frac{x-y+3z}{12+20+45}=\frac{7}{77}=\frac{1}{11}\)

\(\Rightarrow\hept{\begin{cases}x=\frac{1}{11}.12=\frac{12}{11}\\-y=\frac{1}{11}.20=\frac{20}{11}\\3z=\frac{1}{11}.45=\frac{45}{11}\end{cases}}\)

\(\Rightarrow\hept{\begin{cases}x=\frac{12}{11}\\y=-\frac{20}{11}\\z=\frac{45}{11}:3=\frac{15}{11}\end{cases}}\)

Vậy \(\hept{\begin{cases}x=\frac{12}{11}\\y=\frac{-20}{11}\\z=\frac{15}{11}\end{cases}}\)

23 tháng 10 2023

\(\dfrac{2x+4}{x^3-1}-A=\dfrac{2}{x-1}-\dfrac{x+2}{x^2+x+1}\)

\(\Leftrightarrow\dfrac{2\left(x+2\right)}{\left(x-1\right)\left(x^2+x+1\right)}-A=\dfrac{2}{x-1}-\dfrac{x+2}{x^2+x+1}\)

\(\Leftrightarrow A=\dfrac{2\left(x+2\right)}{\left(x-1\right)\left(x^2+x+1\right)}-\dfrac{2}{x-1}+\dfrac{x+2}{x^2+x+1}\)

\(\Leftrightarrow A=\dfrac{2\left(x+2\right)}{\left(x-1\right)\left(x^2+x+1\right)}-\dfrac{2\left(x^2+x+1\right)}{\left(x-1\right)\left(x^2+x+1\right)}+\dfrac{\left(x+2\right)\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(\Leftrightarrow A=\dfrac{2x+4-2x^2-2x-2+x^2-x+2x-2}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(\Leftrightarrow A=\dfrac{-x^2+x}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(\Leftrightarrow A=\dfrac{-x\left(x-1\right)}{\left(x-1\right)\left(x^2+x+1\right)}\)

\(\Leftrightarrow A=\dfrac{-x}{x^2+x+1}\)