Hi, I must solve this inequality. How must I proceed?
I don't know how to, couse I cant do this: so... I know its stupid, but... im a little bit stupid I think.
critical values are , , and
check the original inequality with a value from each of the four intervals defined by the critical values of x ... if the value makes the original inequality true, then all values of x in that interval make the inequality true.
if false ... all values of x in that interval will not work.
I've realized that I could "pass" the couse it won't change signs.
But now I have the second derivative and I must analize its sign for the concave intervals. So, I know the solution actually, but if I proceed the same way than before I can't "pass" the couse it would change the sign.
How should I think this?