SOLUTION: please help me solve this. I am not so good at word problems. The monthly profit in dollars that Carla makes on the sale of x automobiles is determined by the formula p=x^2 -4x-5.

Question 524208: please help me solve this. I am not so good at word problems.
The monthly profit in dollars that Carla makes on the sale of x automobiles is determined by the formula p=x^2 -4x-5. What values of x is her profit positive?
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
p=x^2-4x-5
find the roots
equate to 0
x^2-4x-5=0
x^2-5x+x-5=0
x(x-5)+1(x-5)=0
(x-5)(x+1)=0
x= 5 OR -1
-1 is not possible
so she has to sell more than 5 cars to make a profit
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