Friday

October 24, 2014

October 24, 2014

Posted by **Watermelon** on Thursday, November 24, 2011 at 7:04am.

- AP calculus -
**Damon**, Thursday, November 24, 2011 at 7:36am+ 4 = change from term to term

x-4 + x + x+4 = 75

3 x = 75

x = 25

so

21, 25, 29

- AP calculus -
**Andrew**, Thursday, November 24, 2011 at 7:39amThink about how you can locate these three consecutive terms.

What is the first term, and the common difference?

The sum of an AP for the first n terms is given by

S(n) = (n/2)(2a+(n-1)d)

where a = -7, d = 4

So lets say the 3 consecutive terms are the 14,15 and 16th term.

to get the sum of 75 of these 2 terms, i take

S(16) - S(13)

hence,

S(n) - (n-3) = 75

substituting the formula,

(n/2)(2a+(n-1)d) - [(n-3)/2][2a+(n-3-1)d] = 75

solve and find n.

**Answer this Question**

**Related Questions**

Math (Geometric Progression) - 5 distinct positive reals form an arithmetic ...

Math - 5 distinct positive reals form an arithmetic progression. The 1st, 2nd ...

AP Calculus - The 9th term of an arithmetic progression is 4+5p and the sum of ...

AP calculus - The consecutive terms of an arithmetic progression are 5-x, 8, 2x...

Arithmetic - The first, second and third terms of a geometric progression are 2k...

Math - A sequence is called an arithmetic progression of the rst order if the di...

Maths - 1..The first 2 terms of a geometric progression are the same as the ...

arithmetic - Two arithmetic progression have thd same first and last terms.the ...

maths - 1) The first term of arithmetic progression is -20 and the sum of it's ...

MATH - What value of p are 2p-1,7 and 3P three consecutive terms of ARITHMETIC ...