Answer:
a = - 1
Step-by-step explanation:
given a quadratic in standard form : y = ax² + bx + c : a ≠ 0
Then the x-coordinate of the vertex is
• 
= - 
The line of symmetry passes through the parabola, hence x-coordinate is 4
y = ax² + 8x - 3 is in standard form
with a = a, b = 8 and c = - 3, hence
- 
= 4 ( multiply both sides by 2a
- 8 = 8a ( divide both sides by 8 )
a = - 1
= it is equal to because the absolute value of |-5| is 5
Answer:
A sinusoidal model would be used
The kind of function that have consistency in the periodic rate of change is the Average rate of changes
Step-by-step explanation:
The type of model that would be used is sinusoidal model and this is because there is periodic change in the values given ( i.e the rate of changes given )
For percentage rate of changes :
starting from 0.9% there is an increase to 1.3% then a decrease to 1.1% and a further decrease to 1% before an increase to 1.3% and another decrease to 1%
For Average rate of changes:
starting from 2.9 there is a decrease to 2.4, then an increase to 3.7 and another decrease to 3.1 followed by an increase to 3.6 and a decrease back to 3.2
This relation ( sinusoidal model ) is best suited for a linear model because there is a periodic rate of change in the functions
The kind of function that have consistency in the period rate of change is the Average rate of changes
Speed of the plane: 250 mph
Speed of the wind: 50 mph
Explanation:
Let p = the speed of the plane
and w = the speed of the wind
It takes the plane 3 hours to go 600 miles when against the headwind and 2 hours to go 600 miles with the headwind. So we set up a system of equations.
600
m
i
3
h
r
=
p
−
w
600
m
i
2
h
r
=
p
+
w
Solving for the left sides we get:
200mph = p - w
300mph = p + w
Now solve for one variable in either equation. I'll solve for x in the first equation:
200mph = p - w
Add w to both sides:
p = 200mph + w
Now we can substitute the x that we found in the first equation into the second equation so we can solve for w:
300mph = (200mph + w) + w
Combine like terms:
300mph = 200mph + 2w
Subtract 200mph on both sides:
100mph = 2w
Divide by 2:
50mph = w
So the speed of the wind is 50mph.
Now plug the value we just found back in to either equation to find the speed of the plane, I'll plug it into the first equation:
200mph = p - 50mph
Add 50mph on both sides:
250mph = p
So the speed of the plane in still air is 250mph.
