If x varies inversely as y, and x = 11 when y = 15, find x when y = 3. a: 11/5 b: 33/15 c: 55

55

Step-by-step explanation:

The equation of inverse variation is

y = k/x,

where k is a constant.

We can use the given x- and y-coordinates to find k.

y = k/x

15 = k/11

k = 165

The inverse variation equation for this problem is

y = 165/x

For y = 3,

3 = 165/x

3x = 165

x = 55

C

Step-by-step explanation:

given x varies inversely as y then the equation relating them is

x = ← k is the constant of variation

To find k use the given condition x = 11 when y = 15

k = xy = 11 × 15 = 165 , hence

x = ← inverse variation equation

when y = 3, then

x = - 55 → C

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204