# Arithemetic progression

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the sum of 18term of an A.P is549 given the common difference is 3 find the 56th term and the sum of its 32term

• Arithemetic progression -

term(18) = a+ 17d
but d = 3 and term(18) = 549

a + 17(3) = 549
a = 498

term(56) = a + 55d = .....

sum(32) = (32/2)(2(498) + 31(2) ) = ...

• Arithemetic progression -

unless he meant that S18 = 549
In that case,

18/2(2a+17*3) = 549
a = 5

T56 = 5+55*3 = 170

S32 = 32/2(2*5+31*3) = 1648

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