Come valuti # 9x ^ 2 + 30x + 25 #?

This is a special product - a square of a binomial. So what you do first is to get the square root of the first term. You must get the square root of #9x^2# che è #3x#. Then, you get the square root of 25 which is 5. Put them together but leave a space in the middle for the sign. Since the middle term is positive, we put a plus sign so the final answer is #(3x+5)^2#.