find three terms in AP such that their sum is12 ans the sum of their product is 108
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EXPLANATION.
→ Three terms of an Ap their sum is = 12
→ The sum of their products is = 108
→ Let the three terms of an Ap =
( a - d) , a, ( a + d)
→ a - d + a + a + d = 12.
→ 3a = 12
→ a = 4
→ ( a - d) ( a)(a + d) = 108
→ (a) ( a² - d² ) = 108
→ Put the value of a = 4
→ 4 ( 4² - d² ) = 108
→ 4 ( 16 - d² ) = 108
→ 64 - 4d² = 108
→ - 4d² = 108 - 64
→ - 4d² = 44
→ -d² = 11
→ d² = -11
→ d = -√11
→ Three number are
( a - d) = ( 4 - (-√11)) = ( 4 + √11 )
( a) = 4
( a + d) = 4 - √11
→ series are → ( 4 + √11), 4, ( 4 - √11 ) .
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