F(5) = -1 would be the correct answer.
The geometric sequence is found in the relationship between consecutive terms that is constant.
In this problem, as I understand it, none of the functions forms a geometric sequence.
The functions that form a geometric sequence have the form
f (x) = h (a) ^ n where "a" is the constant relation between the successive terms.
If you wrote the function "f (x) = - 2 (3/4) x", you wanted to write instead:
f (x) = - 2 (3/4) ^ x
So that would be the function that forms a geometric sequence, where the relation between the consecutive terms is 3/4.
You can test it by dividing f (x) / f (x-1)
Then you will see that the result of that division will be 3/4.
What you need to do is do the formula of Area=1/2×Height (Base B +Base A) Base B is bottom Base A is the top then you divide by 2 In this case 1/2 ×8/1 ×(12+15)=108
Perimeter is the border around something...you add all the sides. So you you'll add 5+5=10 , 8+8=16 , and then you add 10+16=26. The answer is 26.