Answer:
dy/dx = -5y - y/x
Step-by-step explanation:
In xy + 5x = 30
Differentiating xy implicitly
y + xdy/dx
Assuming u = xy
In xy = In u
Differentiating In u = 1/u = 1/xy
Differentiating 5x = 5 and differentiating a constant (30) = 0
1/xy(y + xdy/dx) + 5 = 0
(y + xdy/dx)/xy = -5
(y + xdy/dx) = -5xy
xdy/dx = -5xy - y
dy/dx = = (-5xy - y)/x
dy/dx = -5y - y/x
x = number of packages he bought
y = number of popsicles in each package
Here are the two equations:
xy = 54
x = 3 + y
Using the substitution method, you can solve them to find x and y.
(3 + y)y = 54,
3y + y^2 = 54
y^2 + 3y - 54 = 0
Solve the quadriatic equation:
(y +9)(y - 6) = 0
y = -9, 6.
Plug y into: xy = 54
x(-9) = 54, x = -6.
x(6) = 54, x = 9.
So he bought 9 packages of popsicles, bc you can't bye -6 packages.
Answer:
C
Step-by-step explanation:
When completing the square, we essentially want to create a perfect square trinomial by adding a constant.
If we have the following expression:

And we want to complete the square, we will need to divide the b-coefficient by half and then square it.
Thus, the added term should be:

In the given equation, we have:

The b term here is 8. Therefore:

The value we would add would be 16.
The answer is C.
Further notes:
To complete the square, add 16 like mentioned earlier. However, we also need to subtract 16 to balance things out:

The expression inside the parentheses is now a perfect square trinomial. Factor it:

And we are done!