Direct variation has the form y=kx. Given a point we can solve for the constant k.
y=kx, when y=9 and x=-3 becomes:
9=-3k
k=-3 so the constant of variation is negative 3
Answer:
200 miles
Step-by-step explanation:
one inch = 50 miles, 4 × 50 = 200
Here is how to solve it:
<span>Distance1 ÷ (plane velocity + wind velocity) = Distance2 ÷ (plane velocity - wind velocity)</span>800 / (180 + wv) = 640 / (180 - wv)
115,200 +640 wv = 144,000 - 800 wv
1,440 wv = 28,800
wind velocity = 20 mph
Source:
http://www.1728.org/veloccal.htm
Yes you have the right idea. You find the derivative to get the velocity function and then determine when the velocity is zero. That turns out to be at t = 2 and t = 6. Both are correct. The final answer is correct.
The only flaw I see is that you wrote
x'(t) = 3y^3 - 24t + 36
on line 2 when it should be
x'(t) = 3t^2 - 24t + 36
Other than that it looks perfect.
