Answer:
Step-by-step explanation:
1.
Dependent variable: a
Independent variable: c
2.
(in this order)
x = 9
x = 15
x = 4
x = 36 (assuming that says x = 12 * 3)
I'll abbreviate
and
, so the identity to prove is

On the left side, we can simplify a bit:


Then

So the establish the original equality, we need to show that

Combine the fractions:

We can rewrite the denominator as

then using the fact that
, we get

so that we have

as desired.
The answer is A.
I used the formula for finding the vertex of a parabola and I got the first answer choice. So A is correct. :)
We split [2, 4] into
subintervals of length
,
![[2,4]=\left[2,2+\dfrac2n\right]\cup\left[2+\dfrac2n,2+\dfrac4n\right]\cup\left[2+\dfrac4n,2+\dfrac6n\right]\cup\cdots\cup\left[2+\dfrac{2(n-1)}n,4\right]](https://tex.z-dn.net/?f=%5B2%2C4%5D%3D%5Cleft%5B2%2C2%2B%5Cdfrac2n%5Cright%5D%5Ccup%5Cleft%5B2%2B%5Cdfrac2n%2C2%2B%5Cdfrac4n%5Cright%5D%5Ccup%5Cleft%5B2%2B%5Cdfrac4n%2C2%2B%5Cdfrac6n%5Cright%5D%5Ccup%5Ccdots%5Ccup%5Cleft%5B2%2B%5Cdfrac%7B2%28n-1%29%7Dn%2C4%5Cright%5D)
so that the right endpoints are given by the sequence

for
. Then the Riemann sum approximating

is

The integral is given exactly as
, for which we get

To check: we have
