74,000 is your answer
Hope this helps
Well, the answer will depend on whether the order will count or not (based on Permutations and Combinations). <em>If the order counts</em>, then we would use the formula for Permutations, which is:
Where n is the number of items you have, and r is the number of times you choose from the items.
Which simplifies to
Which simplifies to 15*14*13 (because all the numbers 1-12 in the factorial canceled out), which gets us the answer
2730.
Now, if you wanted to find the number of ways to order the toys without replacement (<em>order doesn't count</em>), you would use the formula:
The variables are still the same, but you are now multiplying by r!.
Simplifies to
Which simplifies to (using the same cancellation method above)
Dividing 2730 by 3! will get us an answer of
455.
Really, it depends on whether they are ordered or not. In this case (since you didn't specify whether the order mattered), the answer would be
455 or
2730.
:)
Divide both sides by to get
Substitute , so that . Then
The remaining ODE is separable. Separating the variables gives
Integrate both sides. On the left, split up the integrand into partial fractions.
Then
On the right, we have
Solving for explicitly is unlikely to succeed, so we leave the solution in implicit form,
and finally solve in terms of by replacing :
I think it is a compressed spring.
hope it helps