Here is an example to use the CAS for the BAC 2013 (french exam)

http://www.lexpress.fr/education/bac-2013-le-sujet-de-maths-et-son-corrige_1259225.html

EXERCICE 2

Keystroke :

(a+b*LN(x))/x STO> f(x)

f'

Simplif

solve([f(1)=2;f'(1)=0],[a,b])

2 STO> a

2 STO> b

f(x)

simplif

lim x->0 f(x)

lim x->+oo f(x)

Screen display :