Find the center and the radius and the center of the circle with the given equations:

3. (-1 , 3) , 4

4. (0 , -7), 8

Step-by-step explanation:

circle: (x-h)² + (y-k)² = r²

3. x²+2x+y²-6y-6 =0

  (x²+2x+1) + (y²-6y+9) -16 =0

  (x+1)² + (y-3)² = 4²

center(-1 , 3)      radius: 4

4. x²+y²+14y-15=0

   (x+0)² + (y²+14y+7²) - 64 = 0

   (x+0)² + (y+7)² = 8²

center: (0 , -7)     radius: 8

the revenue of the fitness center, y, is the product of two factors: the number of members and the fee paid by each member. there are 320 members now, but number of members goes down by 10 for each $5 increase in fees, so if x is the number of $5 price increases then members is equal to (320 - 10x). since the fee is currently $45, and the fee increases by $5 for every price bump x, the fee is given by (45 + 5x). so, revenue y is given by y = (320 - 10x)(45 + 5x).