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christinewilliams

  • 2 years ago

given the terms a1 = 5 and a 4= 14 of an arithmetic sequence what is a20

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  1. ghazi
    • 2 years ago
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    \[T _{20}=a _{1}+(n-1)d\] we need d

  2. ghazi
    • 2 years ago
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    now, \[a _{4}=a _{1}+(n-1)d, a _{4}=5+(4-1)d, 14=5+(3)d\] find d and you will have T 20 :)

  3. ghazi
    • 2 years ago
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    \[T _{20}=5+(20-1)d\]

  4. christinewilliams
    • 2 years ago
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    wait..... it is multiple choice it could be 62, 65,171, 185

  5. ghazi
    • 2 years ago
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    well calculate it :) your d=3 i guess then put d in the equation and find it :)

  6. christinewilliams
    • 2 years ago
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    wait what?? so t20=5+(19)3

  7. ghazi
    • 2 years ago
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    correct

  8. christinewilliams
    • 2 years ago
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    I got 62

  9. ghazi
    • 2 years ago
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    thats the answer :)

  10. christinewilliams
    • 2 years ago
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    awesome thank you!!! can you help me with more!!! i am so behind in my math class!

  11. ghazi
    • 2 years ago
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    keep posting :) don't follow up

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