100% - 20% = 80%
$26.95 * 80% = $21.56
You multiply by 80% because you are taking 20% off and now want to know what 80% of the price will be.
-5 could not be used in the table again, because we have the value of x=-5 for the value of 15. Therefore correct option is C.
Answer: C. -5
Answer:
The value of cos Ф is ± 
Step-by-step explanation:
There are important rules for sin Ф and cos Ф
∵ sin Ф = 
∴ sin²Ф = 
∴ sin²Ф = 
→ By using the third rule above
∵ cos²Ф = 1 - sin²Ф
∴ cos²Ф = 1 - 
∴ cos²Ф = 
→ Take square root for both sides
∴ cos Ф = ± 
∴ The value of cos Ф is ± 
Answer:

Step-by-step explanation:
<u>Extended Information </u><u>on</u><u> </u><u>the</u><u> Complex Number System</u>
![\displaystyle \sqrt{-1} = i \\ -1 = i^2 \\ -i = i^3 \\ 1 = i^4\:[all\:multiples\:of\:four]](https://tex.z-dn.net/?f=%5Cdisplaystyle%20%5Csqrt%7B-1%7D%20%3D%20i%20%5C%5C%20-1%20%3D%20i%5E2%20%5C%5C%20-i%20%3D%20i%5E3%20%5C%5C%201%20%3D%20i%5E4%5C%3A%5Ball%5C%3Amultiples%5C%3Aof%5C%3Afour%5D)
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