Finding minimum value - BEST METHOD?!

[fjafarli2021]

I remember from my high school teacher that to find minimum value of x in quadratic equation (ax^2 + bx + c), min. value of x has a formula and it can be found by -b/2a. I think Greg does not mention this in his videos.

e.g. y = x^2 + 4x + 4 which is (x+2)^2

finding min value of x: (-4)/(2*1) = -2.

e.g. y = x^2 - 5x - 6 which is (x-6)(x+1)

finding min value of x: (-5)/(2*1) = -2.5

Good luck in GRE preparation!

[HoldMyBeer]

additional info to understand this correctly:https://www.onlinemath4all.com/find-the-maximum-and-minimum-value-of-quadratic-function.html

[Leaderboard]

@fjafarli2021

I think Greg does not mention this in his videos.

Because this can be done easily by completing the square.

[mosesazu13]

Considering how complicated completing the square can be sometimes, I think this deserves a mention. Not to mention, it can be used to find the minimum of y.