Step-by-step explanation:
In my opinion the reason 4 is incorrect
5*4^2-3*4*5=80-60=20
Hope that helps you
Polygon Diagonals. The number of diagonals in a polygon = n(n-3)/2, where n is the number of polygon sides. For a convex n-sided polygon, there are n vertices, and from each vertex you can draw n-3 diagonals, so the total number of diagonals that can be drawn is n(n-3).
9.5000032 is one such number
9b - 12b² factorised would be 3b(3 - 4b).
You can find this as you must first find a common factor between 9b and -12b², which would be 3b. We can then take this out of the bracket and divide both terms by 3b to get the final answer, which leaves us with 3b(3 - 4b).
I hope this helps!