the first term of an arithmetic sequence is one and the sum of the first four terms is 100. find the first four terms
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Here,
a=1,
S₄ = 100
⇒ 4/2 [2×1 + (4-1)×d] = 100
⇒2 [2 + 3d] = 100
⇒2 + 3d = 50
⇒3d = 50 - 2
⇒3d = 48
⇒d = 16
Thus, the first four terms are a, a+d, a+2d, a+3d.
i.e. 1, 17, 33, 49.
a=1,
S₄ = 100
⇒ 4/2 [2×1 + (4-1)×d] = 100
⇒2 [2 + 3d] = 100
⇒2 + 3d = 50
⇒3d = 50 - 2
⇒3d = 48
⇒d = 16
Thus, the first four terms are a, a+d, a+2d, a+3d.
i.e. 1, 17, 33, 49.
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