Simplify the following:
(4 x^2 + 7 x + 9) - (2 x^2 + 10 x + 4)
Factor 2 out of 2 x^2 + 10 x + 4:
4 x^2 + 7 x + 9 - 2 (x^2 + 5 x + 2)
-2 (x^2 + 5 x + 2) = -2 x^2 - 10 x - 4:
-2 x^2 - 10 x - 4 + 4 x^2 + 7 x + 9
Grouping like terms, 4 x^2 - 2 x^2 + 7 x - 10 x - 4 + 9 = (4 x^2 - 2 x^2) + (7 x - 10 x) + (9 - 4):
(4 x^2 - 2 x^2) + (7 x - 10 x) + (9 - 4)
4 x^2 - 2 x^2 = 2 x^2:
2 x^2 + (7 x - 10 x) + (9 - 4)
7 x - 10 x = -3 x:
2 x^2 + -3 x + (9 - 4)
9 - 4 = 5:
=2x^2 - 3x + 5
