Posted by Anonymous on Friday, November 4, 2011 at 6:17am.
term(3) = a+2d
term(8) = a+7d
a+7d = 5(a+2d)
a+7d = 5a + 10d
-4a = 3d
a = -3d/4
in the same way
a+6d = (a+3d) + 9
3d = 9
d = 3
then a = -9/4
first 5 terms are: -9/4, 3/4, 15/4, 27/4, 39/4
or -2.25, .75 , 3.75, 6.75, 9.75
check:
term(8) = 18.75
term(3) = 3.75
what is 5(3.75) ?
term(7) = 15.75
term(4) = 6.75 , do they differ by 9 ? ,YES
No
-2.5,.75,3.75,6.75,9.75