Recall that

Dividing both sides by cosh²(x) gives

Also, recall the identity

Then

Answer:
y = 7 - 2x/3
Step-by-step explanation:
Make the y alone, so 3y = -2x+21
Divide everything else by 3, so y = -2x/3 +7
You end with the answer of y= 7-2x+3
Answer:
30+4+0.7+0.05
Step-by-step explanation:
Because the expanded form is added the number.
3=30
4=4.
7=0.7
and 5=0.05 so all together is 30+4+0.7+0.05