SOLUTION: NEEDING HELP WITH THIS QUESTION PLEASE. f(x) = 3x2 − 12x + 8 INCREASING=? DECREASING=? HOW DO I FIND/WHAT FORMULA DO I USE TO FIND THIS? THANK YOU!

Algebra ->  Graphs -> SOLUTION: NEEDING HELP WITH THIS QUESTION PLEASE. f(x) = 3x2 − 12x + 8 INCREASING=? DECREASING=? HOW DO I FIND/WHAT FORMULA DO I USE TO FIND THIS? THANK YOU!       Log On


   

Question 993369: NEEDING HELP WITH THIS QUESTION PLEASE.
f(x) = 3x2 − 12x + 8
INCREASING=?
DECREASING=?
HOW DO I FIND/WHAT FORMULA DO I USE TO FIND THIS?
THANK YOU!
Answer by Theo(13342) About Me  (Show Source):
You can put this solution on YOUR website!
you look at what the highest order exponent term is doing.
it's 3x^2
when x is negative, x^2 is positive, so this function should be increasing on the left and on the right.
here's what the graph looks like:
graph%28600%2C600%2C-5%2C5%2C-20%2C20%2C3x%5E2+-+12x+%2B+8%29

here's a good reference on figuring out how to analyze these.

http://www.wtamu.edu/academic/anns/mps/math/mathlab/col_algebra/col_alg_tut35_polyfun.htm