Question

Find the interval on which the curve of y= the integral from 0 to x of 2/(1+3t+t^2)dt is concave up.

I asked this question yesterday and I would like to see if someone could check my answer. I got the curve is concave up when x<-1.5

Answer 1

Actually I got the curve is concave up when x>-1.5

Answer 2

http://www.wolframalpha.com/input/?i=integral+2dt%2F(t%5E2%2B3+t%2B1)

looks more like your first answer

Answer 3

it is concave up when y" > 0
d/dx 2/(1+3x+x^2) > 0
(2x+3) > 0
x > 1.5