Answer:
-7.5
Alternatively,
-0.5(units^-1) + (-4(units^0)) + (-3(units))
Explanation:
On graph, only clearly defined points:
1. x = -3 , y = 0
2. x = -3 , y = -8
3. x = 5 , y = -4
So for:
1. -3 = c ( + a×(0^2) + b×0)
And
2. -3 = a×((-8)^2) + b×(-8) + c = 64×a + (-8)×b + c
Since c = -3 ==> 64×a - 8×b = 0
Simplified ==> 8×a - b = 0 ==> b = 8×a
3. 5 = a×((-4)^2) + b×(-4) + c = 16×a + (-4)×b + c
Since c = -3 ==> 16×a - 4×b = 5 - (-3) = 8
Simplified ==> 4×a - b = 2
Since b = 8×a ==> 4×a - (8×a) = 2
Simplified ==> 2×a - 4×a = 1
==> -2×a = 1
==> a = -0.5
Since b = 8×a ==> b = 8×(-0.5) = -4
So...
c = -3
b = -4
a = -0.5
Then...
a + b + c = -0.5 - 4 - 3 = -7.5