Answer:
y = 3x² - 42x + 144
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) = (7, - 3), thus
y = a(x - 7)² - 3
To find a substitute (9, 9) into the equation
9 = 4a - 3 ( add 3 to both sides )
12 = 4a ( divide both sides by 4 )
a = 3
y = 3(x - 7)² - 3 ← in vertex form
Expand factor and simplify
y = 3(x² - 14x + 49) - 3
= 3x² - 42x + 147 - 3
= 3x² - 42x + 144 ← in standard form
