Looking at the question. you'll know that it's a subtraction question so that eliminates C and D. Now look at A and B. It says that 33 stamps were used. So that means the answer is not a negative expression. (B) Is Eliminated.
ANSWER : A
You do the implcit differentation, then solve for y' and check where this is defined.
In your case: Differentiate implicitly: 2xy + x²y' - y² - x*2yy' = 0
Solve for y': y'(x²-2xy) +2xy - y² = 0
y' = (2xy-y²) / (x²-2xy)
Check where defined: y' is not defined if the denominator becomes zero, i.e.
x² - 2xy = 0 x(x - 2y) = 0
This has formal solutions x=0 and y=x/2. Now we check whether these values are possible for the initially given definition of y:
0^2*y - 0*y^2 =? 4 0 =? 4
This is impossible, hence the function is not defined for 0, and we can disregard this.
x^2*(x/2) - x(x/2)^2 =? 4 x^3/2 - x^3/4 = 4 x^3/4 = 4 x^3=16 x^3 = 16 x = cubicroot(16)
This is a possible value for y, so we have a point where y is defined, but not y'.
The solution to all of it is hence D - { cubicroot(16) }, where D is the domain of y (which nobody has asked for in this example :-).
(Actually, the check whether 0 is in D is superfluous: If you write as solution D - { 0, cubicroot(16) }, this is also correct - only it so happens that 0 is not in D, so the set difference cannot take it out of there ...).
If someone asks for that D, you have to solve the definition for y and find that domain - I don't know of any [general] way to find the domain without solving for the explicit function).
Each pack would cost $4.99
Isolate the s. Note the equal sign. What you do to one side, you do to the other. Do the opposite of PEMDAS.
Subtract 19 from both sides
7 (-19) = 4s + 19 (-19)
7 - 19 = 4s
-12 = 4s
Isolate the s. Divide 4 from both sides
-12/4 = 4s/4
s = -12/4
s = -3
-3 is your answer for s
hope this helps
Answer:
.30
Step-by-step explanation:
Purchase Cost = Cost per Portion x Portion Per Purchase
16 oz=1lb
