the sum of three terms of an ap is 21 and their product is 231. find the numbers.
This problem is to be solved by using high school math only. The answer is that numbers are 3,7,11. The solution includes assuming that the required numbers be a, a-d, a+d . But i am not able to understand why we are assuming these , since its not given that the numbers is consecutive in the AP, so all we know that they can be of form a, a+nd, a+md . A similar question which says that numbers are consecutive in the given AP has a similar assumption that numbers are a, a-d, a+d. but why can't the numbers be a , a+d , or a+2d?
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If you'll take a+d, a-d and a,
a-d and a+d will multiply to form identity
(a+d)(a-d)= a²-b²
and the sum will be easy to solve rather than
taking a+d and a+2d and solving completely..
hope it helps :)
a-d and a+d will multiply to form identity
(a+d)(a-d)= a²-b²
and the sum will be easy to solve rather than
taking a+d and a+2d and solving completely..
hope it helps :)
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