Answer:
y = 3x² + 54x + 240
Step-by-step explanation:
The equation of a parabola in vertex form is
y = a(x - h)² + k
where (h, k) are the coordinates of the vertex and a is a multiplier
here (h, k) = (- 9, - 3), thus
y = a(x + 9)² - 3
To find a substitute either of the roots into the equation
Using (- 8, 0), then
0 = a(- 8 + 9)² - 3
0 = a - 3 ( add 3 to both sides )
a = 3
y = 3(x + 9)² - 3 ← in vertex form
Expand factor and simplify
y = 3(x² + 18x + 81) - 3
= 3x² + 54x + 243 - 3
= 3x² + 54x + 240 ← in standard form
K/3 + 4 = 10
K/3 = 10 - 4
K/3 = 6
K = 6x3
K = 18
We know that 1 litre is equal to 1000ml (double the amount they're giving us), so 1 litre of paint is going to be $23 (we know this by multiplying 11.50 • 2).
Knowing this, all we need to do is multiply $23 • 4 which should give us $92.
So, the total of how much you will need to pay in this scenario to paint a room is $92 for 4 litres of blue paint.
Good luck!