Algebra

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I have 3 questions I'm stuck on and would love for someone to explain and show me how to solve them so I can also solve the other one.

Find the partial sum S6
1. An=3n+2

2. Find the number of terms n in an arithmetic sequence if a1=20, d=5, and An=75.

3. Find the general term for 8,17,26,35,44......

  • Algebra -

    3. 8, 8*2+1, 8*3+2, 8*n+n-1

    or An=9n-1

  • Algebra (Partial) -

    3. x + 9

  • Algebra -

    #2
    Term(n) = a+(n-1)d

    75 = 20 + (n-1)(5)
    55 = 5(n-1)
    11 = n-1
    n = 12

    there are 12 terms

  • Algebra -

    Thanks for the help bobpursley and Reiny I appreciate showing how you got to it so I can also do it.

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