Currently studying for my Calculus exam on Monday but am stuck on some particular problem.
I took the first derivative and got:
12x^2 + 30x + 18
Then I factored it:
6(2x^2 + 5x + 3)
Used the quadratic formula and got x=1 and x=1.5
My question is... what do I do after that? srs
Thanks in advance.
(I know there's an official math thread but I would literally have to wait a few days before getting an answer)


05032012, 11:53 PM #1
 Join Date: Jan 2010
 Location: California, United States
 Age: 23
 Stats: 6'0", 185 lbs
 Posts: 5,406
 Rep Power: 5934
Math experts of the misc GTFIH!!! (4k reps)
War is Peace; Freedom is Slavery; Ignorance is Strength.

05032012, 11:57 PM #2

05032012, 11:59 PM #3

05032012, 11:59 PM #4

05042012, 12:00 AM #5

05042012, 12:01 AM #6

05042012, 12:04 AM #7

05042012, 12:05 AM #8
 Join Date: Jan 2010
 Location: California, United States
 Age: 23
 Stats: 6'0", 185 lbs
 Posts: 5,406
 Rep Power: 5934

05042012, 12:07 AM #9
 Join Date: Feb 2011
 Age: 24
 Stats: 5'11", 187 lbs
 Posts: 7,857
 Rep Power: 14216
set the derivative equal to 0. solve for x. plug x back into original equation.
edit: your derivative is completely wrong. da fug mayne.
18 + 30x  12x^2>Engineering Students Who Know Everything About Math, Science, And Everything Crew<
B.S. Chemical Engineering 2013
*Extreme Dips Crew*
160lbs x 3 reps
[Pics or Negs] Crew

05042012, 12:08 AM #10

05042012, 12:09 AM #11

05042012, 12:10 AM #12
 Join Date: Jan 2010
 Location: California, United States
 Age: 23
 Stats: 6'0", 185 lbs
 Posts: 5,406
 Rep Power: 5934

05042012, 12:11 AM #13

05042012, 12:11 AM #14

05042012, 12:13 AM #15

05042012, 12:15 AM #16

05042012, 12:15 AM #17

05042012, 12:17 AM #18

05042012, 12:19 AM #19

05042012, 12:20 AM #20

05042012, 12:21 AM #21
 Join Date: Jan 2010
 Location: California, United States
 Age: 23
 Stats: 6'0", 185 lbs
 Posts: 5,406
 Rep Power: 5934

05042012, 12:24 AM #22

05042012, 12:37 AM #23
 Join Date: Jan 2010
 Location: California, United States
 Age: 23
 Stats: 6'0", 185 lbs
 Posts: 5,406
 Rep Power: 5934
Alright, here we go.
This is from the '11 test.
f'(x)= 6x^2  18x  24
6(x^2  3x  4)
Quadratic formula
x=4;x=1
x=4
x=1
x=2
x=7
Plug all of these numbers into the original equation and I get
x@2= 11
x@1= 28
x@4= 97
x@7= 92
Abs max = f(7)
Abs min = f(4)
Does that look correct?War is Peace; Freedom is Slavery; Ignorance is Strength.

05042012, 12:47 AM #24
 Join Date: Dec 2010
 Location: Brooklyn, New York, United States
 Stats: 6'2", 185 lbs
 Posts: 13,395
 Rep Power: 12650
f'(x) = 6x^2  18x  24
6(x^2 3x 4)
6(x4)(x+1)
x=4
x=1
f(4)
f(1)
f(0)
f(2)
f(7)
I didn't plug them in but I think you're good to go OP. Good job.
Just a something to remember for the exam, incase your professor tries to phuck with you:
If any of your roots are not in the intervals given, then you don't have to plug them in.
So if you had an x = 8 in this case, you would just ignore it.◄ Stim Dick Mafia ►
[FREE DOITBIG191]

05042012, 12:49 AM #25

05042012, 12:58 AM #26

05042012, 01:02 AM #27
Bookmarks