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matte!/ likning

Posted: 03/04-2006 18:32
by joda..
4a i annen - 2(a+1)(2a-3)

løs likningen[/i]

Posted: 03/04-2006 18:40
by Knut Erik
4a[sup]2[/sup] - 2(a + 1)(2a - 3)
= 4a[sup]2[/sup] - 2(2a[sup]2[/sup] - 3a + 2a - 3)
= 4a[sup]2[/sup] - 4a[sup]2[/sup] + 6a - 4a + 6
= 2a + 6
= 2(a + 3)

Posted: 03/04-2006 18:41
by Guest
Vi skal løse [tex]4a^2 - 2(a+1)(2a-3) = 0[/tex], tror jeg du mente.

Gang ut parentesen:

[tex](a+1)(2a-3) = 2a^2 -3a +2a - 3 = 2a^2-a-3[/tex]

sett dette inn:

[tex]4a^2 - 2(2a^2 - a -3) = 4a^2 - 4a^2 + 2a +6 = 2a + 6[/tex]

da blir det enklere:

[tex]2a+6 = 0[/tex] gir [tex]a=-3[/tex]