Question 1088206
a(1) = 2k +1
a(2) = 2k+1 +d
a(3) = 2k+1 +2d
:
5k-3 = 2k+1 +d
1) 3k-d = 4
:
7k-2 = 2k+1 +2d
2) 5k-2d = 3
:
equations 1) and 2) are 2 equations in 2 unknowns - we can solve them by substitution
:
solve equation 1 for d
:
3) d = 3k-4
:
substitute for d in equation 2
:
5k -2(3k-4) = 3
5k -6k+8 = 3
k = 5
:
a(1) = 2(5) + 1 = 11
:
use equation 3) to solve for d
:
d = 3(5)-4 = 11
:
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k = 5
a(17) = 11 + 11(17-1) = 187
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