Answer:
Her friend got the better deal.
Step-by-step explanation:
For Jillians equation look at
$22.56/4 = $6.39 per CD
For her friends equation look at
$18.45/3 = $6.15 per CD
Jillian's friend got the better deal because she paid less per CD as shown in the equations above.
Answer:

Step-by-step explanation:
=> 
<u>Using Formula</u> 
<u><em>Where </em></u>
a = 249
b = 248
=> 
=> 
=> 497
Answer:
m∠Q ≈ 53°
Step-by-step explanation:
To find the measure of ∠Q, the law of cosines will need to be used. Lowercase letters represent the side lengths, while upper case letters represent angles.
In this situation, 'A' will be ∠Q. Therefore:
17² = 18² + 20² -2(18)(20)cosQ
Simplify:
289 = 324 + 400 -2(360)cosQ
Continue simplifying down:
-435 = -720cosQ
Divide both sides by '-720':
0.604 = cosQ

m∠Q ≈ 52.83 or 53° rounded to the nearest whole degree.
The square of a prime number is not prime.
a) let x ∈ R, If x ∈ {prime numbers}, then
∉{prime numbers}
there says that if x is a real and x is in the set of the prime numbers, then the square of x isn't in the set of prime numbers.
b) Prove or disprove the statement.
ok, if x is a prime number, then x only can be divided by himself. Now is easy to see that
= x*x can be divided by himself and x, then x*x is not a prime number, because can be divided by another number different than himself