S1 2013 høst LØSNING

Oppgave 1

$f(x)= 3x^2+3x+1 \qquad D_f = \R \\f'(x)= 6x-3 \\f´(2)= 6 \cdot 2 -3 = 9$

Oppgave 2

a)

$x(x+5)-10 =4 \\ x^2+5x-14=0 \\ x= \frac{-5\pm \sqrt{25+56}}{2} \\x= -7 \vee x=2$

b)

$10^{3x} -100000 =0 \\ 10^{3x} = 10^5 \\ 3x=5 \\ x=\frac 53$

Oppgave 4

a)

$v=v_0+at \\t = \frac{v-v_0}{a}$

b)

$t = \frac{v-v_0}{a} \\ t = \frac{25-1}{3}=8 $

Oppgave 5

a)

$ \frac{9^2a^2b^3}{(3ab^2)^2} \\ =\frac{3^4a^2b^3}{3^2a^2b^6} \\ = 3^{4-2} \cdot a^{2-2} \cdot b^{3-6} \\ = 3^2b^{-3} \\ = \frac{9}{b^3} $

b)

$\lg (\frac{a^2}{b^2}) + \lg( \frac {b^2}{a}) + lg (a+b) \\ =\lg a^2 - \lg b^2 + \lg b^2 - \lg a + \lg (a+b) \\= 2\lg a - \lg a + \lg(a+b) \\ = \lg a + \lg (a+b) \\ =lg (a(a+b)) \\ =\lg (a^2+ab)$

Oppgave 8

a) f(x)=0