\(a,=10x-15x^2-2+3x-x^2+9=-16x^2+13x+7\\ b,=xy^5-\dfrac{1}{4}x^2+2\\ c,=\left(2x-1\right)\left(4x^2+2x+1\right):\left(2x-1\right)=4x^2+2x+1\\ d,=\left(x^3+5x^2-3x+x^2+5x-3\right):\left(x^2+5x-3\right)\\ =\left(x^2+5x-3\right)\left(x+1\right):\left(x^2+5x-3\right)\\ =x+1\)