Answer:
70
Step-by-step explanation:
The question is:
Check whether the function:
y = [cos(2x)]/x
is a solution of
xy' + y = -2sin(2x)
with the initial condition y(π/4) = 0
Answer:
To check if the function y = [cos(2x)]/x is a solution of the differential equation xy' + y = -2sin(2x), we need to substitute the value of y and the value of the derivative of y on the left hand side of the differential equation and see if we obtain the right hand side of the equation.
Let us do that.
y = [cos(2x)]/x
y' = (-1/x²) [cos(2x)] - (2/x) [sin(2x)]
Now,
xy' + y = x{(-1/x²) [cos(2x)] - (2/x) [sin(2x)]} + ([cos(2x)]/x
= (-1/x)cos(2x) - 2sin(2x) + (1/x)cos(2x)
= -2sin(2x)
Which is the right hand side of the differential equation.
Hence, y is a solution to the differential equation.
Answer:
Step-by-step explanation:
Answer:
There are 14,400 possible ways to do this
Step-by-step explanation:
Here, we have a selection problem. What to use is combination obviously.
For a combination problem, we would be selecting a specific number from a given total. For a case where we have n number of things and we are looking for how many ways to select r number of things, this can be done in nCr ways and this is mathematically equal to n!/(n-r)!r!
For the Diet coke, she has 10 bottles and want to select 3 for tasting, the number of ways she can do this is mathematically equal to 10C3. Computationally this is equal to ;
10!/(10-3)!3! = 10!/7!3! = 120 ways
For the coke zero, we have the same pattern, selecting a total number of 3 out of 10. This means the same 10C3 with the answer being 120 ways also.
Now, the number of ways of selecting from both would be a multiplication of both answers which is 120 ways * 120 ways = 14,400 ways
