12.60 / 7 = $ 1.80 per bottle
10.98 / 6 = $ 1.83 per bottle
18.10 / 10 = $ 1.81 per bottle
16.38 / 9 = $ 1.82 per bottle
best buy (cheapest) is : $ 12.60 for 7 bottles <==
20
Step-by-step explanation:
20 gfhhfgjgifjdgxgjcjhxg
2x2-5x-18=0
Two solutions were found :
x = -2
x = 9/2 = 4.500
Step by step solution :
Step 1 :
Equation at the end of step 1 :
(2x2 - 5x) - 18 = 0
Step 2 :
Trying to factor by splitting the middle term
2.1 Factoring 2x2-5x-18
The first term is, 2x2 its coefficient is 2 .
The middle term is, -5x its coefficient is -5 .
The last term, "the constant", is -18
Step-1 : Multiply the coefficient of the first term by the constant 2 • -18 = -36
Step-2 : Find two factors of -36 whose sum equals the coefficient of the middle term, which is -5 .
-36 + 1 = -35
-18 + 2 = -16
-12 + 3 = -9
-9 + 4 = -5 That's it
Step-3 : Rewrite the polynomial splitting the middle term using the two factors found in step 2 above, -9 and 4
2x2 - 9x + 4x - 18
Step-4 : Add up the first 2 terms, pulling out like factors :
x • (2x-9)
Add up the last 2 terms, pulling out common factors :
2 • (2x-9)
Step-5 : Add up the four terms of step 4 :
(x+2) • (2x-9)
Which is the desired factorization
Equation at the end of step 2 :
(2x - 9) • (x + 2) = 0
Step 3 :
Theory - Roots of a product :
3.1 A product of several terms equals zero.
When a product of two or more terms equals zero, then at least one of the terms must be zero.
We shall now solve each term = 0 separately
In other words, we are going to solve as many equations as there are terms in the product
Any solution of term = 0 solves product = 0 as well.
Essentially, we are trying to find the missing constant term of 
(remember that we are subtracting 
due to the negative sign in front of the second term). Let's expand this to see what we can work with:
Now, we know the second term is 
, so let's set the second term in the polynomial we just found equal to :
- Divide both sides of the equation by
- Divide both sides of the equation by 2
We have found . We know the missing constant term is 
, according to the polynomial we found earlier. Thus, the missing term is:
The missing constant term is 36.
