Hey! Your rational number would be 
Answer:
5
Step-by-step explanation:
5+12= 17
Answer:
option A.) y-3 = 1/16 (x-2)^2
Step-by-step explanation:
we know that
If the axis of symmetry is parallel to the y-axis, then we have a vertical parabola
The equation of a vertical parabola is equal to

where
(h,k) is the vertex
In this problem we have
(h,k)=(2,3)
p=4
substitute

The rule of a function is:
You CANNOT have one x-value with multiple different y values in the same function. You can however have different x values with the same y value.
Also for reference: independent means x value and dependent means y- value.
The first answer is not a function because as you can see there is one x-value with multiple y values.
second answer IS a function because as I said before you can have different x values with the same y value
third answer is a function again because you can have different x values with same y value
number four isn't a function bc again the -2 x value has 2 different y Values.
T = How tall they are.
Robin = 180
His brother = x cm shorter
T = 180 - x