<span>f(x) = ax2+bx+c, is quadratic equation
</span><span>function opening downward if the a<0,
</span><span>kf(x) = -x², a= -1<0
so the answer is </span><span>B.kf(x) </span><span>
</span>
X is equal to 8. The work for that is on the attached picture.
Answer:
(a) 12 hours
(b) $220
Step-by-step explanation:
(a) First we plug in $364 for C
C=76+24h
364=76+24h
Subtract 76 from both sides
24h=288
Divide both sides by 24
h=12
She spent 12 hours fixing the drain
(b) First we plug 6 hours in for h
C=76+24(6)
Multiply it out
C=76+144
Add
C=220
It costs $220 for fixing a drain that takes 6 hours
Answer: d. (17, 20)
Step-by-step explanation:
We have the following system of equations:
(1)
(2)
Isolating 
from (1):
(3)
Substituting (3) in (2):
(4)
Isolating 
:
(5)
(6)
(7)
Substituting (7) in (1):
(8)
Isolating :
(9)
Hence, the correct option is d. (17, 20)
