Answer:
Step-by-step explanation:
the solution is right
x^2-6x-7=0:
x^2-6x-7=0
(add 7 to both sides)
x^2-6x=7
x^2-6x+9=7+9  (the coefficient of x² will be used to divide all sides)for here its 1, it will remain same ,
 then we get the coefficient of x, divide it by 2 and square it and add it to both sides
which is like these
x²-6x=7
the coefficient of x is -6
-6/2 = -3, square it (-3)² = 9
then add 9 to both sides 
x^2-6x+9=7+9
simplifiy the squares on the left hand side
x²+9 = (x-3)²
(x-3)^2=16
√(x-3)^2 )=±√16
x-3=± 4
x=-3±4
then simplify each sign
x=-3+4            x=-3-4
x=1                   x=-7
 
        
                    
             
        
        
        
Step-by-step explanation:
Divide 140 by  to represent the amount of hours he worked.
 to represent the amount of hours he worked.
To make dividing easier,  can also represent 2.8 as a decimal.
 can also represent 2.8 as a decimal.

He has worked 50 hours after completing 140 rows of grapes.
 
        
             
        
        
        
Answer:
 3 strain would still alive after 48 hours
Step-by-step explanation:
Initial population of virus = 40000 grams 
A certain virus is dying off at a rate of 18% per hour. 
We are supposed to find  how much of the  strain would still be alive after 48 hours
Formula : 
 =Initial population
=Initial population
N(t)= Population after t hours 
r = rate of decrease = 18% = 0.18
t = time = 48 hours 
So,the  strain would still be alive after 48 hours=
Hence 3 strain would still alive after 48 hours
 
        
             
        
        
        
Answer:I think 0.4
Step-by-step explanation: Hope this helps
 
        
             
        
        
        
The answer is : impossible