Question 203171
e monthly profit P (in dollars) that Jim makes on the sale of x mobile homes is determined by the formula P=x^2+5x-50. Find the values of x for which Jim makes a profit.
:
A profit is made when P > 0 (positive)
:
Solve the equation:
x^2 + 5x - 50 = 0
Factor this to
(x+10)(x-5) = 0
Two solutions:
x = 5
We can say when x > 5, he makes a profit
and
x = -10
We can say when x < -10 he makes a profit
:
See if that is true; test it for x=6
P = 6^2 + 5(6) - 50
P = 36 + 30 - 50
P = +16
:
If x = -12
P = -12^2 +5(-12) - 50
P = 144 - 60 - 50
P = +34
:
:
A graph illustrates this; P is on the y axis
{{{ graph( 300, 200, -16, 16, -100, 100, x^2+5x-50) }}}
Note the value of P is negative between -10 and + 5