You didn't give us the equation, but circle equations are in the form;
(x-h)^2 + (y-k)^2 =r^2 where h and k are the x and y coordinate of the center and r is the radius of the circle squared. 
        
             
        
        
        
Answer:
The height of the tree in 2020 was of 19.63 feet.
Step-by-step explanation:
Exponential equation for growth:
The exponential equation for the growth of an amount has the following format:

In which H(t) is the amount after t years, H(0) is the initial amount and r is the growth rate, as a decimal.
A 4 foot tree was planted in 2012 outside a high school.
This means that 
The tree grew continuously by 22% each year from that point.
This means that 
Find out what the height of the tree was in 2020.
2020 is 2020 - 2012 = 8 years after 2012, so this is H(8). 




The height of the tree in 2020 was of 19.63 feet.
 
        
             
        
        
        
Answer:
I'm not 100% but I think it could be x4 and then +5?
Step-by-step explanation:
 
        
             
        
        
        
The slope is 6 and the y-intercept is -8
        
                    
             
        
        
        
Answer:
25 cent stamps = 13 and 29 cent stamps = 15
Step-by-step explanation:
x = 25 cent stamps and y = 29 cent stamps
x + y = 28......x = 28 - y
0.25x + 0.29y = 7.60
0.25(28 - y) + 0.29y = 7.60
7 - 0.25y + 0.29y = 7.60
-0.25y + 0.29y = 7.60 - 7
0.04y = 0.60
y = 0.60 / 0.04
y = 15 <===== 29 cent stamps
x + y = 28
x + 15 = 28
x = 28 - 15
x = 13 <===== 25 cent stamps
lets check it...
0.25x + 0.29y = 7.60
0.25(13) + 0.29(15) = 7.60
3.25 + 4.35 = 7.60
7.60 = 7.60 (correct..it checks out)