Explanation:
5x + 6x + 3x
= 14x.
Now we compare the expressions with the result:
11x + 3x = 14x. (correct)
14x + x = 15x. (incorrect)
2(3x + 4x) = 2(7x) = 14x. (correct)
3x(2 + 1) + 5x = 3x(3) + 5x = 9x + 5x = 14x. (correct)
5x + 3(2x + x) = 5x + 3(3x) = 5x + 9x = 14x. (correct)
Hence our answers are the 1st, 3rd, 4th and 5th.