first AS:
first term: a
d = 9
n = 21
term(21) = a + 9(20) = a + 180
2nd AS
first term : a
d = 4
term(n) = a + 4(n-1)
a + 4(n-1) = a + 180
4n - 4 = 180
4n = 184
n = 46 <----- number of terms for the 2nd sequence
check
term(21) for the first = a + 180
term(46) for the second = a + 4(45) = a + 180 , the same as the last term of sequence #1
looks like the first term could be anything, as long as it is the same for both
Two APS have the same first and last terms.The first AP has 21 terms with a common differences of 9. How many terms has the other ap if its common differences is 4.
1 answer