Answer:
Problem 1) frequency: 160 heartbeats per minute, period= 0.00625 minutes (or 0.375 seconds)
Problem 2) Runner B has the smallest period
Problem 3) The sound propagates faster via a solid than via air, then the sound of the train will arrive faster via the rails.
Step-by-step explanation:
The frequency of the football player is 160 heartbeats per minute.
The period is (using the equation you showed above):

second problem:
Runner A does 200 loops in 60 minutes so his frequency is:
loops per minute
then the period is: 0.3 minutes (does one loop in 0.3 minutes)
the other runner does 200 loops in 65 minutes, so his frequency is:
loops per minute
then the period is:

Therefore runner B has the smaller period
This problem can be solve by graphing (technology), as suggested.
The answer is posted as an attached image. We see that after about 14.75 years, the invading species will surpass the indigenous population.
If it needs to be solved mathematically and accurately, the math is a little more advanced, using the bisection method, or Newton's method.
However, we can also do that by trial and error, starting from 14.75. It is easier than you might think.
Post if you would like to have more information on one or the other methods.
Note: the scale of y has been shrunk by 1000, so each unit on the y-axis represents 1000 frogs.
Cos 200= -0.939692621. cos 115-sin200=-0.080598118 Sin 115=0.906307787
I'm doing that practice rn too tell me if you got the answer!
6x+3>3x+30
The thing about solving inequalities, you just need to treat the symbol, which is the less than symbol in this case, as an equal sign.
So our problem becomes: 6x+3=3x+30
Now we solve this like a normal algebra problem.
First, get all the variables on one side. Since 3x is smaller than 6x, we'll get rid of that by subtracting it from each side.
3x+3=30 is what we end up with.
Now to get the variable alone and get rid of that constant. To do that, we are going to subtract 3 from each side.
We end up with 3x=27
Now, to get the 'x' alone, we need to divide each side by 3.
x=9 is what we end up.
BUT WE FORGOT TO DO SOMETHING
We started this as an inequality problem, so we need to end it as an inequality solution.
Since there wasn't any negatives we need to worry about (Which is something else entirely) we just need to transfer the symbol we started with down.
x>9
Any Questions?