The Sum Of three terms of an ap is 21 and the product of first and third term exceeds the second term by 6. Find the terms
Answers
Answer:
Follow the steps given below
Explanation:
Let a = 1st term, d = common difference
Then the 1st 3 terms are a, a + d, a + 2d
Their sum is 3a + 3d = 21, so a + d = 7, and
thus d = 7 - a.
The problem says a(a + 2d) = a + d + 6
a^2 + 2ad = a + d + 6 Substitute:
a^2 + 2a(7 - a) = a + (7 - a) + 6
a^2 + 14a - 2a^2 = 13, or
a^2 - 14a + 13 = 0
(a - 1)(a - 13) = 0, so a = 1 or a = 13
If a = 1, d = 6; if a = 13, d = - 6. So there
are 2 possible sequences: 1, 7, 13... or 13, 7, 1...
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Explanation:
Given : -
- The sum of an AP is 21 and product of th first .
- third term exceed the second term by 6.
To Find : -
- Find the 3 terms
Solution : -
- Let a = 1st term,
- d = common difference
Then the 1st 3 terms are a, a + d, a + 2d
Their sum is 3a + 3d = 21, so a + d = 7, and
thus d = 7 - a.
The problem says a(a + 2d) = a + d + 6
Substitute all values :
a² + 2ad = a + d + 6
a²+ 2a(7 - a) = a + (7 - a) + 6
a² + 14a - 2a² = 13
a² - 14a + 13 = 0
(a - 1)(a - 13) = 0
a = 1 or a = 13
If a = 1, d = 6; if a = 13, d = - 6.
So there are 2 possible sequences: 1, 7, 13..or 13, 7, 1