Sun, 05/04/2015 - 09:24
#1
Challenging Math, anyone?
The sum of the first 100 terms of an arthmetic progresion is 15050.The first,third and eleventh terms of this progression are 3 consecutive terms of a geometric progression.Find the first term, and common difference of the arithmetic progression.
yh
sum of n terms of an AP=n/2[2a+(n-1)d]
1st a
3rd a+2d
11th a+10d
a+2d/a=a+10d/a+2d
6a-4d=0......... eqt 1
2a+99d=1505......eqt 2
a simulteneuos equation
solve.
try that.
yessss me , i need help!!