a = 5
b = 4x² - 2x - 6
The area is:
a · b = 5(4x² - 2x - 6) = 20x² - 10x - 30
Or you can add areas of shapes:
- blue: 5 · 4x² = 20x²
- pink: 5 · (-2x) = -10x
- green: 5 · (-6) = -30 <- a little strange, the length of a side shouldn't be negative
Sum of those areas is the area of entire rectangle: 20x² - 10x - 30
But the first option is easier here.
