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koli123able

The sum of four numbers in A.P is 20. The ratio of the product of the first and the last numbers and the product of 2nd & 3rd numbers is 2:3 ; Find the numbers . . . ANSWER = 2,4,6,8 OR 8,6,4,2

  • one year ago
  • one year ago

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  1. koli123able
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    Cant understand how to start

    • one year ago
  2. sauravshakya
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    Let four numbers in AP be a-3d ,a-d ,a+d and a+3d

    • one year ago
  3. sauravshakya
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    Now, a-3d+a-d+a+d+a+3d=20 4a=20 a=5

    • one year ago
  4. sauravshakya
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    Also, (a-3d)(a+3d)/ {(a-d) (a+d)} =2/3

    • one year ago
  5. koli123able
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    i cant understand this sentence "The ratio of the product of the first and the last numbers and the product of 2nd & 3rd numbers is 2:3"

    • one year ago
  6. sauravshakya
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    It simply means (a-3d)(a+3d)/ {(a-d) (a+d)} =2/3

    • one year ago
  7. koli123able
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    oh

    • one year ago
  8. koli123able
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    what should i do next.. cross multiply?

    • one year ago
  9. sauravshakya
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    Now, 3(a-3d)(a+3d) =2(a-d)(a+d) 3a^2 -27d^2 =2a^2 -2d^2 a^2 =25d^2 Also a=5 5^2 =25d^2 d^2=1 d=+-1

    • one year ago
  10. sauravshakya
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    Now, can u?

    • one year ago
  11. koli123able
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    ok

    • one year ago
  12. koli123able
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    i have to substitute the values of a and d in the four numbers which were a-3d, and so on

    • one year ago
  13. sauravshakya
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    yep

    • one year ago
  14. koli123able
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    ok got the numbers :)

    • one year ago
  15. koli123able
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    thanks

    • one year ago
  16. sauravshakya
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    welcome

    • one year ago
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