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The sum of the three numbers in A.P is 21 and the product of the first and third number of the sequence is 45. What are the three numbers?
Answer & Solution
Correct Answer:
Option
D
Let the numbers are be a - d, a, a + d
Then a - d + a + a + d = 21
3a = 21
a = 7
and (a - d)(a + d) = 45
a2 - d2 = 45
d2 = 4
d = $$ \pm $$ 2
Hence, the numbers are 5, 7 and 9 when d = 2 and 9, 7 and 5 when d = -2. In both the cases numbers are the same.
Then a - d + a + a + d = 21
3a = 21
a = 7
and (a - d)(a + d) = 45
a2 - d2 = 45
d2 = 4
d = $$ \pm $$ 2
Hence, the numbers are 5, 7 and 9 when d = 2 and 9, 7 and 5 when d = -2. In both the cases numbers are the same.
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