Lowest possible terms mean lowest individual power terms. In order to change the equation in lowest possible terms, we first write all power terms adjacent to each other in decreasing order of power with their sign and then do mathematical operation of addition and subtraction as per their sign.
Write down following equation in lowest possible terms:-5x5+4x3+6+3x2-4x4-3x5-2x3-3x2+19
now we will write as below:
then add/subtract coefficient of same power term as per sign '+'/'-'