Answer: 7x + 70
Step-by-step explanation:
A.
We can rewrite the squared in two ways.
The first way is to rewrite it as a multiplication, this is:

The second way to rewrite the squared is by using the formula for this kind of product:

B.
Once again we can find the final result using each of the options given in part A, for the first option we have:

For the second option we have:

No matter which way we choose the answer for the squared is:
Answer:
See below
Step-by-step explanation:
Considering
, then

This is the Cauchy–Schwarz Inequality, therefore

We have the equation

We can use the Cauchy–Schwarz Inequality because
and
are greater than 0. In fact,
. Using the Cauchy–Schwarz Inequality, we have

and the equation holds for


Therefore, once we can write

It is the same thing for cosine, thus

Once


dividing both numerator and denominator by
, we get

Therefore, it is proved that
