R1 2008 vår LØSNING

Del 1

Oppgave 1

a)

<tex>f(x) = x^2 \cdot lnx \\ f'(x) = 2x \cdot lnx + \frac 1x \cdot x^2 = 2xlnx+x = (2lnx+1)x</tex>

b)

<tex>(x^3-4x^2+x+6):(x-2) =x^2 \\ -(x^3-2x^2)</tex>

c)

<tex>\lim_{x\to 8} \frac{x^2-64}{2x+16} =\lim_{x\to 8} \frac{(x-8)(x+8)}{2(x-8)}= \lim_{x\to 8} \frac{(x+8)}{2}=8 </tex>

d)

<tex>lg(x \cdot y^2)-2lgy+ lg(\frac{x}{y^2}) = lgx + 2lgy - 2lgy +lgx - 2lgy = 2(lgx-lgy)= 2lg ( \frac xy)</tex>

e)

1)

2)