Questions: P=-76 x^3+4810 x^2-320,000, 0 leq x leq 60
Using this model, find the smaller of two advertising amounts that will yield a profit of 2,490,000. (Round your answer to the nearest thousands of dollars.)
x
Transcript text: \[
P=-76 x^{3}+4810 x^{2}-320,000, \quad 0 \leq x \leq 60
\]
Using this model, find the smaller of two advertising amounts that will yield a profit of $\$ 2,490,000$. (Round your answer to the nearest thousands of dollars.)
$\$$ $\square$ $x$
Solution
Solution Steps
Step 1: Define the Profit Equation
The profit function is given by
\[
P = -76x^3 + 4810x^2 - 320,000
\]
We need to find the values of \( x \) such that
\[
P = 2,490,000
\]
This leads us to the equation:
\[
-76x^3 + 4810x^2 - 320,000 - 2,490,000 = 0
\]
which simplifies to
\[
-76x^3 + 4810x^2 - 2,810,000 = 0
\]
Step 2: Solve for Roots
Using numerical methods, we find the roots of the cubic equation. The calculated roots are approximately
\[
39.0796, \quad 39.0796, \quad 45.1601
\]
Step 3: Filter Valid Roots
We need to filter these roots to find those that lie within the range \( 0 \leq x \leq 60 \). The valid roots are
\[
0.0, \quad 0.0, \quad 0.0
\]
Step 4: Identify the Smaller Root
Among the valid roots, the smallest value is
\[
0.0
\]
Final Answer
The smaller of the two advertising amounts that will yield a profit of \$2,490,000 is