Posted by Aliza on Monday, January 21, 2013 at 5:16am.
Find the no. of terms
Solve each problem.
1. In the Arithmetic sequence 5,8,11,14.... what is n if a sub n is 32?
2.Find the sum of the first 20 terms of the arithmetic sequence -15,-7,31,43...
Math - Reiny, Monday, January 21, 2013 at 10:34am
1. term(n) = a+(n-1)d
you have a = 3, d = 2 , n = ??
33 = 3 + (n-1)(2)
30 = 2n - 2
28 = 2n
n = 14 ------ there are 14 terms
do the 2nd one the same way
for the other two, I don't know how you defined a sub n
for the last:
first find the number of terms in the same way I showed you
you have a = -15 , d = 12 , n = ?
once you find a and d
Sum(n) = (n/2)(2a + (n-1)(d) )
Math - Anonymous, Tuesday, January 22, 2013 at 6:52am
Thank you so much . 1. In the Arithmetic sequence 5,8,11,14.... what is n if an is 32?
1. In the Arithmetic sequence 5,8,11,14.... what is n if n is 32?
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