Expand the following:
(3 x+7) (3-2 x)
(3 x+7) (3-2 x) = (3 x) (3) + (3 x) (-2 x) + (7) (3) + (7) (-2 x):
-2 3 x x+3 3 x-2 7 x+7 3
3×3 = 9:
-2 3 x x+9 x-2 7 x+7 3
3 x (-2) x = 3 x^2 (-2):
-2×3 x^2+9 x-2 7 x+7 3
3 (-2) = -6:
-6 x^2+9 x-2 7 x+7 3
7×3 = 21:
-6 x^2+9 x-2 7 x+21
7 (-2) = -14:
-6 x^2+9 x+-14 x+21
Grouping like terms, -6 x^2+9 x-14 x+21 = -6 x^2+(9 x-14 x)+21:
-6 x^2+(9 x-14 x)+21
9 x-14 x = -5 x:
Answer: |
| -6x^2+-5x+21
