a: \(x\left(2x+1\right)-x^2\left(x+2\right)+\left(x^3-x+3\right)\)
\(=2x^2+x-x^3-2x^2+x^3-x+3\)
=3
b: \(0,2\left(5x-3\right)-\dfrac{1}{2}\left(\dfrac{2}{3}x+6\right)+\dfrac{2}{3}\left(3-x\right)\)
\(=x-0,6-\dfrac{1}{3}x-3+2-2x\)
\(=-\dfrac{4}{3}x-1,6\) có phụ thuộc vào biến