Question

4[2x – 3.1(x2 + 2x) + 7.2x]

Answer 1

4[2x – 3.1(x^2 + 2x) + 7.2x]
= 4[2x – 3.1x^2 - 6.2x + 7.2x]
= 4[- 3.1x^2 + 3x]
= -12.4x^2 + 12x

Answer 2

The answer to this question is 4 (.2 x - 3.1 (x2 + 2 x)).  Try using Wolfram for future questions - it's a sort-of calculator like website.