Which property was used to simplify the expression? 3c+ 9 + 4c = 3c + 4c + 9

a: distributive property
b: commutative property
c: associative property
d: inverse property

The change that happened from the first half of the equation to the second half was you moved the 9 and the 4c around.
Commutative property of addition allows you to do that. It's what says that 2+3 is the same thing as 3+2

First locate the turning point (vertex) of the graph. which is at the coordinates x=5 and y=9 or (5; 9).to determine whether it's a maximum or mininum value, you have to discern whether the vertex's y-value is the highest value or lowest value the graph can reach. since the vertex's y-value, 9 is the highest value the graph can reach, it will be a maximum.another basic way to determine whether the vertex's value is max or min is to see if the graph is smiling or sad. if it's smiling, the turning point/vertex would be a minimum, while a sad parabola would have a maximum y-value at the vertex.