H2 Mathematics Questions

• zJenJenz

  17 Apr 11, 23:08

  Hello!

  Here are 3 APGP questions.

  https://picasaweb.google.com/lh/photo/Z4ov6Jd_5rS7quSIODsWU9xDabKu20fLTVW6sJigg7k?feat=directlink

  https://picasaweb.google.com/lh/photo/2SLKm4BKHoyxOgDBRyWRntxDabKu20fLTVW6sJigg7k?feat=directlink

  https://picasaweb.google.com/lh/photo/tmde-7ylMCrjFUCDKOkpUNxDabKu20fLTVW6sJigg7k?feat=directlink

  I've been working on them for a while, but cant seem to get the answer...

  Could you help me?

  Thank you!

  Jennifer

• wee_ws

  18 Apr 11, 08:44

  Hi,

    For Q1, consider the middle pearl's value to be the first term.

    Thanks.

  Cheers,
  Wen Shih

• wee_ws

  18 Apr 11, 08:50

  Hi,

    For Q2, draw a diagram. Then consider layer 1, layer 2, etc.

    Thanks.

  Cheers,
  Wen Shih

• StudiousZerg

  19 Apr 11, 17:12

   

  For Q3, the "trick" is to do the other series by visualizing the last term as the first. Then the arithmetic progression is just -d.

  So we get (k/2) [2a + 2d(n-1)] + (k-1)d] ---- *

  The other one is just the normal (k/2) [2a + (k-1)d]. ---- **

  Taking * minus **, you should solve your problem directly.