The sum of the 4th and 6th terms of an AP is 42.the sum of the 3rd and 9th terms of the progression is 52. Find the first term.the common difference and the sum of the first ten terms of the progression
The sum of the 4th and 6th terms of an AP is 42
---> a+3d + a+5d = 42
2a + 8d = 42
the sum of the 3rd and 9th terms of the progression is 52
---> a+2d + a+8d = 52
2a + 10d = 52
subtract them:
2d = 10
d = 5
sub into 2a+8d=42
2a+40 = 42
a = 1
sum(10) = 5(2(1) + 9(5)) = 235