Please use "^" to denote exponentiation. "x2" doesn't cut it.
Simplify: 3.5x^2+9(7.1+0.5)+4
We must carry out operations in a certain order. Here, you must do any operations within parentheses first, followed by exponentiation, followed by mult. and div., followed by add. and subtr.
Thus, we get 3.5x^2 + 9(7.6) + 4
... which comes out to 3.5x^2 + 31.5 + 4
Cannot do anything further with 3.5x^2; all we can do is to add 31.5 and 4:
3.5x^2 + 35.5 (answer)