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



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ghazi
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\[T _{20}=a _{1}+(n1)d\] we need d

ghazi
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now, \[a _{4}=a _{1}+(n1)d, a _{4}=5+(41)d, 14=5+(3)d\] find d and you will have T 20 :)

ghazi
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\[T _{20}=5+(201)d\]

christinewilliams
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wait..... it is multiple choice it could be 62, 65,171, 185

ghazi
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well calculate it :) your d=3 i guess then put d in the equation and find it :)

christinewilliams
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wait what?? so t20=5+(19)3

ghazi
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correct


ghazi
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thats the answer :)

christinewilliams
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awesome thank you!!! can you help me with more!!! i am so behind in my math class!

ghazi
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keep posting :) don't follow up