B
Step-by-step explanation:
The maximum value of the function is the y- coordinate of the vertex.
Given a parabola in standard form
y = axΒ² + bx + c ( a β 0 )
Then the x- coordinate of the vertex is
= -
y = - 3xΒ² - 15x + 9 β is in standard form
with a = - 3 and b = - 15, thus
= - = - 2.5
Substitute x = - 2.5 into the equation for y- coordinate of vertex
y = - 3(- 2.5)Β² - 15(- 2.5) + 9 = - 18.75 + 37.5 + 9 = 27.75 β B