You can use the discriminant rule, which is :
b^2 -4ac
“exactly one solution” means that it is equal to zero
so: 
b^2 -4(4)(9)=0
b^2 -4(36)=0
b^2 -144=0
b^2=144
square root both sides
b=12 or -12
hope this helps !
        
                    
             
        
        
        
2x^2 - 4 = 68
add 4 to both sides
2x^2 = 72
divide both sides by 2
x^2 = 36
find the square root of each sides
x = 6, -6
ANSWER: the positive value of x is 6
        
             
        
        
        
Answer:
14 elliptical machines
Step-by-step explanation:
t = # of treadmills
e = # of elliptical machines
t + e = 38
t = e + 10
Substitute:
e + 10 + e = 38
2e = 28
e = 14
 
        
             
        
        
        
Answer:
60
Step-by-step explanation:
when you multiply 100 by .6 it equals 60
 
        
                    
             
        
        
        
F(x)=y=2x+3
P (1,5)
Substitute x and y:
5=2*(1)+3
5=5 true
Point P (1,5) is on the graph of f.