Answer:
and 
Step-by-step explanation:
(a)
A =
× 4
× 
= 2
× 
=
×
← rationalise the denominator
=
units²
(b)
Using Pythagoras' identity in the right triangle
let hypotenuse be h , then
h² = (4
)² + (
)²
= 32 + 
=
+ 
=
( take the square root of both sides )
h =
=
×
← rationalise the denominator
h = 
Part A: Yes, the data represent a function. The definition of a function is a relation in which no value of x will have two different values of y.
(Every time you plug in 3 as x, you will always get 4 as y; it's ok if you plug in 3 and 5 as x and get the same y, you just can't get two different y's for one x; sorry, it is pretty confusing). None of the numbers in the table repeat, so we can safely say that the relation is a function.
Part B: All we have to do is plug in 11 for x in the function given to find the answer:

In the table, y = 8 when x = 11, but in the function given, y = 34 when x = 11, so the function given is greater.
Part C: To find the answer to C, just plug in 99 for f(x), as it tells you to do:
1 gallon (it’s stayed in the question)
The average of 4, 9, 16, 25 and x is 2x means that;
(4+9+16+25+x)/5=2x
Multiply both side by 5
5(54+x)/5=2x(5)
54+x=10x
Subtract x to both side
54+x-x=10x-x
54=9x
Divided 9 to both side
54/9=9x/9
x=6
Check:
Substitute x with 6
(4+9+16+25+x)/5=2x
(4+9+16+25+6)/5=2(6)
60/5=12
12=12; so x=6 which marks B as the correct answer. Have a nice day!