I believe it's 3 because 4 times 3 equals 12 and 12 plus 8 equals 20!
4(3)+8=20
Hoped this helped! :)
Given:
t = 1/2 √v
v = speed of object meters per second
t = 3 seconds
3 = 1/2 √v
3 * 2 = √v
6 = √v
6² = √v²
36 meters = v
v = 36 meters per second
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Explanation:</h2><h2>
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The diagram is missing but I'll assume that the arc BDC is:

And another arc, let's call it FGH. measures:

If those arc are equal, then this equation is true:

Substituting k into the first equation:

I would help but I don't speak your language do u speak English not being mean
Step-by-step explanation:
Exponential function is given by general form 
Where a and b are constants.
say a=1 and b=2 then we can write function as :

or 
To graph this or any exponential function, we just need to find some points then join them by a curved line.
Like plug x=0, 1, 2,... into above function and find points:
plug x=1

Hence point is (1,2)
Find more points similarly then graph them to get the graph as shown below: