# Completing the square [finding a maximum and minimum value]?

• Mar 4th 2009, 01:26 PM
db5vry
Completing the square [finding a maximum and minimum value]?
If I had the quadratic expression of x^2 + 6x - 4, and wrote it as (x + 3)^2 + 5, what would be the minimum and maximum values of this and why?
• Mar 4th 2009, 01:55 PM
e^(i*pi)
Quote:

Originally Posted by db5vry
If I had the quadratic expression of x^2 + 6x - 4, and wrote it as (x + 3)^2 + 5, what would be the minimum and maximum values of this and why?

The minimum value would be 5. This would occur at x = -3 because a squared value cannot be negative so it will be a minimum when (x+3) = 0.

The maximum would be infinity
• Mar 4th 2009, 01:58 PM
chella182
When completing the square of $x^2+6x-4$ I get $(x+3)^2-13$ since $(x+3)^2=x^2+6x+9$, so to get from 9 to -4 you need to minus 13.