Lời giải:
a.

$5x-[2x+1-(2x-3)-(4x+1)]=5x-(2x+1-2x+3-4x-1)$

$=5x-(-4x+3)=5x+4x-3=9x-3$

b.

$(-3x^2+2x-1)+(4x^2-2x+3)$

$=-3x^2+2x-1+4x^2-2x+3=x^2+2$

bằng 2^2 =4 

Ta có: \(\dfrac{2x+3}{1-x^2}+\dfrac{2x+1}{x^2-2x+1}\)

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

\(=\dfrac{\left(-2x-3\right)\left(x-1\right)}{\left(x-1\right)^2\cdot\left(x+1\right)}+\dfrac{\left(2x+1\right)\left(x+1\right)}{\left(x+1\right)\cdot\left(x-1\right)^2}\)

\(=\dfrac{-2x^2+2x-3x+3+2x^2+2x+x+1}{\left(x-1\right)^2\cdot\left(x+1\right)}\)

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

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

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

=2^2=4

b)\(\left(2x^3-3x^2+6x-9\right)\left(2x-3\right)\)

\(=\left[x^2\left(2x-3\right)+x\left(2x-3\right)\right]\left(2x-3\right)\)

\(=\left(2x-3\right)\left(x^2+x\right)\left(2x-3\right)\)

\(=\left(2x-3\right)^2\left(x^2+x\right)\)

tự làm tiếp đi nha

tiếp câu b)

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

a, \(\left(2x+1\right)^2+\left(2x-1\right)^2-2\left(2x+1\right)\left(2x-1\right)\)

\(=\left(2x+1\right)^2-2\left(2x+1\right)\left(2x-1\right)+\left(2x-1\right)^2\)

\(=\left[2x+1-\left(2x-1\right)\right]^2\)

\(=\left(2x+1-2x+1\right)^2=2^2=4\)

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

\(=\left(2x+3-2x-5\right)^2\)

\(=\left(-2\right)^2=4\)

ĐKXĐ: \(x\ne0;x\ne\pm1\)

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

\(=\dfrac{3}{2x\left(x+1\right)}+\dfrac{2x-1}{\left(x-1\right)\left(x+1\right)}-\dfrac{4}{2x}\)

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

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

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

\(=\dfrac{1}{2x\left(x-1\right)}\)

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

Kết bạn với tôi đi ,tôi cô đơn quá 

1.(2x+3).(x-5)+2x(3-x)+x-10

=2x^2 -10x+3x-15+6x-2x^2+x-10

=2x-25

2.(-x-2)³+(2x-4).(x²+2x+4)-x².(x-6)

=-x^3+6x^2-12x-8+2x^3+4x^2+8x-4x^2+8x-16-x^3+6x^2

D = (2x+3)² - 2(2x-1)(2x+3) + (2x-1)² + 31

D = [(2x+3) - (2x-1)]² + 31

D = (2x + 3 - 2x + 1)² + 31

D = 4² + 31

D = 16 + 31

D = 47