The product of three consecutive terms of a G. P. is 5832 and their sum is 57. Find the three terms
Answers
Solution :-
Let us assume that three terms in GP are a, ar and ar² .
So,
→ a * ar * ar² = 5832
→ a³ * r³ = 5832
→ (ar)³ = 5832
→ (ar)³ = (18)³
→ ar = 18 ----- Equation (1)
and,
→ a + ar + ar² = 57
→ a + ar² = 57 - 18
→ a + ar² = 39
→ a + ar * r = 39
→ a + 18r = 39
→ a = (39 - 18r)
putting value of a in Equation (1),
→ (39 - 18r) * r = 18
→ 18r² - 39r + 18 = 0
→ 6r² - 13r + 6 = 0
→ 6r² - 9r - 4r + 6 = 0
→ 3r(2r - 3) - 2(2r - 3) = 0
→ (2r - 3)(3r - 2) = 0
→ r = (3/2) and (2/3)
when r = (3/2)
→ a * (3/2) = 18
→ a = 12
then three terms are :-
- a = 12
- ar = 18
- ar² = 27
and, when r = (2/3)
→ a * (2/3) = 18
→ a = 27
then three terms are :-
- a = 27
- ar = 18
- ar² = 12
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