You can put this solution on YOUR website!
Showing polynomial long division is a little difficult.
The first part will show the factor (left hand column), then the factor times the divisor,
then the next line will show the subtraction.
Then repeat.
Hopefully it makes sense.
.
.
...........___________________
(x+3)|x^3+2x^2+x+12
x^2:...x^3+3x^2
-----------------------------------
.........................-x^2+x+12
-x:...................-x^2-3x
-----------------------------------
...................................4x+12
4:...............................4x+12
-----------------------------------
...............................................0
.