Answer:
Step-by-step explanation:
It is D, I did this quiz once
First set everything to 0.

Giving you A= 1 , B= 1 and C= -5
Then input everything into the quadratic formula and either solve by hand or use a calculator.
Note exact values are found by hand, decimals are found using a calculator.
Bare with me a minute, I am still trying to figure it out. Here is what I have so far.
M5 is the same as m1 so it's 75°
f(x) = -10
set the equation equal to -10 and solve for x:
-10 = -x-1
Add 1 to both sides:
-9 = -x
Divide both sides by -1:
x = 9