SOLUTION: suppose p(x)=-x^2+30x-50 is the profit P(x),in thousands of dollars, for a firm when it sells x thousand units a) What is the firm profit when it sells 1000 units b) What is

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Question 863090: suppose p(x)=-x^2+30x-50 is the profit P(x),in thousands of dollars, for a firm when it sells x thousand units
a) What is the firm profit when it sells 1000 units
b) What is the firms profit when it sells 10,000 units
c) how many units must the firm sell to break even

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
profit P(x),in thousands of dollars, for a firm when it sells x thousand units
p(x)= -x^2+30x-50
a) What is the firm profit when it sells 1000 units: p(1) = 29-50 = -$21,000
b) What is the firms profit when it sells 10,000 units: p(10) = $150,000
c) how many units must the firm sell to break even: 1772 units
-x^2+30x-50 = -(x-15)^2 + 175
x = 1.77124, 28.22875
Solved by pluggable solver: SOLVE quadratic equation with variable
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case -1x%5E2%2B30x%2B-50+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%2830%29%5E2-4%2A-1%2A-50=700.

Discriminant d=700 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28-30%2B-sqrt%28+700+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%2830%29%2Bsqrt%28+700+%29%29%2F2%5C-1+=+1.77124344467705
x%5B2%5D+=+%28-%2830%29-sqrt%28+700+%29%29%2F2%5C-1+=+28.228756555323

Quadratic expression -1x%5E2%2B30x%2B-50 can be factored:
-1x%5E2%2B30x%2B-50+=+-1%28x-1.77124344467705%29%2A%28x-28.228756555323%29
Again, the answer is: 1.77124344467705, 28.228756555323. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+-1%2Ax%5E2%2B30%2Ax%2B-50+%29