As with any long division problem, you start with the most significant terms of the dividend and divisor.
x^3/x = x^2
This is the first term of the quotient.
As with any long division problem, you multiply this by the divisor, subtract from the dividend and repeat.
(x^3 + x^2 + x - 3) - x^2(x-1)
= 2x^2 + x - 3
The second term of the quotient will be
2x^2/x = 2x
The new dividend is
(2x^2 + x - 3) - 2x(x-1)
= 3x - 3
We can see that this is 3(x-1), so the remaining term of the quotient is 3.
The quotient is x^2 + 2x + 3.
This is the first term of the quotient.
As with any long division problem, you multiply this by the divisor, subtract from the dividend and repeat.
(x^3 + x^2 + x - 3) - x^2(x-1)
= 2x^2 + x - 3
The second term of the quotient will be
2x^2/x = 2x
The new dividend is
(2x^2 + x - 3) - 2x(x-1)
= 3x - 3
We can see that this is 3(x-1), so the remaining term of the quotient is 3.
The quotient is x^2 + 2x + 3.