Step-by-step explanation:
4-17x^2+16=0 s 
Calculate multiply 
20-17x^2=0
Reoder the term
-17x^2+20=0
Calculate the discriminat 
D=0^2-4x(-17)x20
Simplify 
D=1360
The quadric equation has 2 real solutions 
So your Solution is :
2 real solutions 
 
        
             
        
        
        
The area of a circle is the size of the 2-dimensional space inside the circle's 
closed curved boundary.
The area can be calculated in terms of known linear measurements of the circle:
-- Area  =  (π) x (radius)²
-- Area  =  (π/4) x (diameter)²
-- Area  =  (1/2) x (circumference) x (radius)
-- Area  =  (1/4) x (circumference) x (diameter)
Any of these formulas will give you the area.  The one you decide to use 
just depends on what you already know about the circle.
        
             
        
        
        
X=700R+85Y
R= Number of Refrigerators
Y= Number of Years 
        
                    
             
        
        
        
Circumference is found with the formula 
c = pi × d
d is diameter and we will use 3.14 for pi.
The diameter is the measure across the center of the circle. In the first problem, you are given the radius, so we have to multiply by 2 to get the diameter. Then we can use the formula.
12.4 in × 2 = 24.8 in (that's the diameter)
c = pi × D
c = 3.14 × 24.8
c = 77.872 inches
circumference is 77.872 inches.
Try the other problems on your own. They are just like this one. Just make sure they are giving you the diameter and not the radius. Post if you have problems.