Help with a homework assignment: profit equation

[gte]

How does this answer look?

6. Show a graph of the profit equation. Be sure to label the horizontal and vertical axes.
• Label the y-intercept with an ordered pair of numbers. Explain these values in the context of the problem.
• Label both x-intercepts with ordered pairs of numbers, approximating values to the nearest tenth. Explain these values in the context of the problem.
• Label the vertex with an ordered pair of numbers. Explain these values in the context of the problem.

6.)

I'm guessing X is items produced and Y is profit? So all numbers should be in the upper right quadrant of the graph where positive X and Y numbers reside?

profit of 0 = $0
profit of 5 = $1518
profit of 10 = $2619
profit of 15 = $3560
profit of 20 = $4341
profit of 25 = $4962
profit of 30 = $5423
profit of 35 = $5724
profit of 40 = $5865
profit of 42 = $5876.6
profit of 45 = $5846
profit of 50 = $5667
profit of 55 = $5328
profit of 60 = $4829
profit of 65 = $4170
profit of 70 = $3351
profit of 75 = $2372
profit of 80 = $1233
profit of 84 = $206.6
profit of 84.7 = 16.45
profit of 84.8 = -10.97
profit of 85 = $-66


I believe the Y intercept is 0 profit (0, 0)
I believe the first X intercept is 0 items (0, 0), with the second being 84.7 items (84.7, 0)
I believe the vertex is 42, 5876.6

[maggiemagnet]

If this is from the first equation you posted, then you can find the exact x-intercepts by plugging zero in for y and then plugging the result into the Quadratic Formula. There's also a formula for the vertex, if you'd like to be exact for that, too.