You are multiply by -2.
term 1: 5
term 2: -10
terms 3: 20
term 4: -40
term 5: 80
term 6: -160
term 7: 320
term 8: -640
So, the 8th term is -640. Hope this helps, please mark brainliest and have an amazing day!
Answer:

Step-by-step explanation:
For this case we know that:

And we want to find the value for
, so then we can use the following basic identity:

And if we solve for
we got:


And if we replace the value given we got:

For our case we know that the angle is on the II quadrant, and on this quadrant we know that the sine is positive but the cosine is negative so then the correct answer for this case would be:

Answer:
11 calls
Step-by-step explanation:
She has already spent 42 min. Also she wants to talk for 2 min per call. We can change calls on x. So, only 2x min for her calls left.
42 + 2x = 64
2x = 64 - 42
2x= 22
x=11
Answer: 11 calls