Um idk how to help it is basically already done
EXPLANATION
If the first two terms of an arithmetic sequence are 7 and 4, then we know that an arithmetic sequence has a constant difference d and is defined by

Check wheter the difference is constant:
Compute the differences of all the adjacent terms:

Replacing terms:
4-7 = -3
The difference between all of the adjacent terms is the same and equal to
d = -3
The first element of the sequence is


Therefore, the nth term is computed by
d= -3

Refine
d= -3 ,

Now, replacing n=7

So, the answer is -11.
Answer:
1. if you are solving using the quadratic formula. the answer is in the first picture.
2. if you are looking to completing the square the answer is in the second picture.
Step-by-step explanation:
X^2 - 8x = (x - 4)^2 - 16
we add 16 to give x^2 - 8x + 16 which is a perfect square
x^2 - 8x + 16 = (x - 4)^2
answer is 16