Answer:
Must add: 202
Step-by-step explanation:
a = x
2ab = 26x
2ab = 26a [ substitute a instead of x]
b= 13
So,
But given equation is :
We have find the difference between 169 and -33 to get the number that should be added to get the perfect square.
That is , 169 - (-33) = 202
Therefore ,
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.
First, change one of the equations to an y=x form I'll use the top one for example.
3x-2y=14
-2y=14-3x
y=-7+(3/2)x
Not that you can show what y is in terms of x, plug in the x side of the equation into the other equation, for y.
x+2(-7+(3/2)x)=10
Now, you can solve for x
x-14+3x=10
4x-14=10
4x=24
x=6
Using this value of x, we can now solve for y using one of the original equations.
(6)+2y=10
2y=4
y=2
A is the first value of the sequence, then you increase or decrease by d each time
Answer:
1 Is A
2 is B
3 is A
4a is D
4b is -53 but that's not an answer choice
4c is C
4d is D
