Question

The archway to the entrance of an art gallery can be model by y= -1/3(x-5)(x+5) where x and y are measured in feet. The x-axis represents the floor. Find the width of the arch at floor level.

Answer 1

x=5 feet

Explanation:

At floor level y=0

If the expression is:

`0=1/3(x-5)(x+5)\\0=1/3(x^2-25)\\0=1/3x^2-25/3\\25/3=1/3x^2\\25=x^2\\x=5`

But, with the negative sign, the answer is x= 5i (where i is imaginary)