EthanTheTutor
If the length and width of a certain rectangle with positive area are both solutions to the equation \(-3x^3+13x^2-11x=0\), what is the area of that rectangle?
a) \(3.\overline{3}\)
b) \(3.\overline{6}\)
c) \(4.\overline{3}\)
d) \(4.\overline{6}\)
e) \(5.\overline{3}\)
\(x=0\) is one solution to the equation \(-3x^3+13x^2-11x=0\), but we are told that the area is positive; thus, none of the sides are equal to zero, and we can discard that possibility.
This allows us to divide by \(x\), giving: \(-3x^2+13x-11=0\). Then, the question is equivalent to asking, "what is the product of the solutions to this quadratic?"
We could use the quadratic formula to find the solutions to this equation, but it will be much easier to remember that the product of the solutions to a quadratic is given by \(\frac{c}{a}\).
In this case, that gives: \(\frac{c}{a}=\frac{-11}{-3}=3.\overline{6}\).
Answer B.