Question

f(x)=x3/3+x2/2 , i need to find its increasing and then decreasing function ! Please Help !!

Answer 1

is this for calculus?

Answer 2

yes

Answer 3

I have find its derivative . x^2+x
and now F(x) > 0 and F(x)<0 i need to find

Answer 4

so what are the 0's of f'(x)?

Answer 5

hello, where are you?

Answer 6

after finding derivative i have to put F(1) and answer is 2

Answer 7

and then find x at a-increasing , b-decreasing and c= neither

Answer 8

here x^2+x>0 (in incraesing)

Answer 9

the 0's of the derivative are 0 and -1. put these on a number line...and pick a point from inside each of the 3 intervals. evaluate f'(x) at those points (actually, just evaluate the sign). if positive, put a + if negative put a -.

Answer 10

i have found the derivative !

Answer 11

first, f'(x) = x(x+1)
draw a number line and put the 0's on it...

Answer 12

now evaluate the sign in each of the intervals...

Answer 13

ok then x belongs to(0,infinity) ?

Answer 14

so increasing in first and third interval, decreasing in 2nd interval. you can check the 2nd derivative to ensure it is concave down then concave up, switching concavity somewhere between -1 and 0.

Answer 15

what are you saying?

Answer 16

ok Thank You ! =)