First,
We are dealing with parabola since the equation has a form of,
Here the vertex of an up - down facing parabola has a form of,
The parameters we have are,
Plug them in vertex formula,
Plug in the 
into the equation,
We now got a point parabola vertex with coordinates,
From here we emerge two rules:
- If
then vertex is max value - If
then vertex is min value
So our vertex is minimum value since,
Hope this helps.
r3t40
Answer:
.
It means that 673 of 9 inch tiles are required to cover an area of 400 square feet, when spacing the tiles a quarter inch apart.
Step-by-step explanation:
Given:
The function relating number of 9 inch tiles required and area to cover is:
Now, plug in 400 for 
to evaluate 
.
Therefore, Don required 673 of 9 inch tiles to cover an area of 400 square feet, when spacing the tiles a quarter inch apart.
Angle 1 is a right angle =90 °
so 5x-85=90
5x=90+85
5x=175
x=35
A = 180
b = 180
c = 180
180+180-180 = 180
