Question 1056891
Unless you can make the bases equal, you can't do much more.  x^3+3y^2 can't be simplified.
x^3+3x^2 can be simplified by factoring out x^2 to get x^2(x+3)
One thing you can do with unlike bases and equal exponents:
x^2*y^2=(xy)^2
They can be put in parentheses and raised to the appropriate power.