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).
Answer: y=9 (point B on the graph)
Step-by-step explanation:
y=3x
x=3
y=3(3) (3×3)
3x3=9
So 9(y)=3(3x)
Point B which is located at the 9 mark
<span>The answer is c. 1.5r + 2.5(5 – r) = 10.50. Let r be the number of raisins and p be the number of peanuts. Raisins cost $1.50 per pound: 1.5r. Peanuts cost $2.50 per pound: 2.5p. Jeremy spends $10.50: 1.50r + 2.50p = 10.50. Jeremy makes 5 pounds of trail mix: r + p = 5. So, we have the system of two equations: 1.5r + 2.5p = 10.50 and r + p = 5. Use the second equation to express p: p = 5 - r. Now, substitute p in the first equation: 1.5r + 2.5(5 - r) = 10.50. Therefore, the correct choice is c. 1.5r + 2.5(5 – r) = 10.50.</span>
<em>Answer:</em>
<em>C</em>
<em>Hope this helps. Have a nice day.</em>
