Answer:
10.2 inches
Step-by-step explanation:
we know that
In this problem we have two cases
First case
The given lengths are two legs of the right triangle
so
Applying the Pythagoras Theorem
Find the length of the hypotenuse
substitute
Second case
The given lengths are one leg and the hypotenuse
so
Applying the Pythagoras Theorem
Find the length of the other leg
substitute
Find the difference between the two possible lengths of the third side of the triangle
so
X = the number of minutes the phone is used
<u>Plan A:</u>
40¢ per minute ($0.40)
no other costs
<em>Cost for 1 month = 0.4 x</em>
<u>Plan B:</u>
$30 a month, even if you don't use the phone at all
100 free minutes
then 50¢ per minute ($0.50)
Cost for 1 month:
If 'x' is less than 100: <em>Cost = 30</em>
<span>
If 'x' is greater than 100</span>:
Cost = 30 + 0.5(x - 100) (Because the first 100 minutes are free, and
you only pay for minutes past 100. There are [x-100] of those.)
Eliminate parentheses: Cost = 30 + 0.5x - 50
Combine like terms: <em> Cost = 0.5x - 20</em>
Which plan costs more ? It depends on how many minutes you use in a month.
If you use a small number of minutes, Plan A costs you more.
If you use a huge number of minutes, Plan B costs you more.
Where is the crossover point ? It's the number of minutes in one month
where the costs of both plans are equal.
<u>If you use the phone for less than 100 minutes a month,</u>
(where the cost of Plan B starts increasing with each minute):
0.4x = 30
Divide each side by 0.4: <em>x = 75</em>
Less than 75 minutes per month, Plan A costs less.
Past 75 minutes a month, Plan A costs more than $30, so Plan B costs less,
until Plan B starts charging for extra minutes.
<u>If you use the phone for more than 100 minutes a month: </u>
0.4 x = 0.5 x - 20
Add 20 to each side: 0.4 x + 20 = 0.5 x
Subtract 0.4x from each side: 20 = 0.1 x
Multiply each side by 10: <em> 200 = x</em>
There it is.
Now we can combine the results:
-- Less than 75 minutes in a month: Plan A costs less.
-- Between 75-200 minutes in a month: Plan B costs less.
-- More than 200 minutes a month: Plan A costs less again.
Complicated ? Absolutely ! That's why citizens' consumer groups are after
these companies, to try to get them to make their plans more understandable
to regular people. I know from personal experience that even a lot of the
salesmen in the phone stores could not figure this out and give you sound advice.
Answer: (2 1/2, 0) (the last option)
Step-by-step explanation:
I guess the function is:
f(x) = (2 1/2) - (3 1/2)*x
now, the rule for f-1(x) that we know is:
f-1( f(x) ) = x.
So if we want to find the x-intercept of f-1(x), we must evaluate it in f(0)
f-1(f(0)) = 0.
And we have that f(0) = (2 1/2) - (3 1/3)*x = 2 1/2
This means that the x-intercept of f-1(x) will be when x= 2 1/2, so the intercept is:
(2 1/2, 0)
I would plot the points (even if it’s a rough graph), but the answer is (1,4)
