"(0,7p²-mg³)(0,7p²+mg³)"

I don't know the context of your question, but the answer you provided "(0,7p²-mg³)(0,7p²+mg³)" seems to be an algebraic expression. It appears to be a difference of squares: the difference between (0,7p²) and (mg³) multiplied by the sum of (0,7p²) and (mg³).