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anonymous

  • one year ago

What are the explicit equation and domain for a geometric sequence with a first term of 4 and a second term of -8? (5 points) an = 4(-2)n - 1; all integers where n ≥ 0 an = 4(-2)n - 1; all integers where n ≥ 1 an = 4(-12)n - 1; all integers where n ≥ 1 an = 4(-12)n - 1; all integers where n ≥ 0

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  1. anonymous
    • one year ago
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    i know it's a or b but i don't know how to find the domain

  2. campbell_st
    • one year ago
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    what do you think the common ratio is...? so 4 x r = -8 r = ?

  3. anonymous
    • one year ago
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    i told you.. I know it's a or b i just don't know the domain

  4. anonymous
    • one year ago
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    wait no isn't the common ratio -8/4

  5. anonymous
    • one year ago
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    bc it's 2nd term divided by first

  6. campbell_st
    • one year ago
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    ok... so if you know its a or b look at a and substitute n = 0 into the equation.... what do you get..?

  7. campbell_st
    • one year ago
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    well the common ratio is the value you multiply the 1st term by to get the 2nd etc... it can be found by dividing the 2nd term by the 1st term...

  8. campbell_st
    • one year ago
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    but what happens when you substitute n = 0

  9. anonymous
    • one year ago
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    how do i find the domain is what I'm asking

  10. anonymous
    • one year ago
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    nvm

  11. anonymous
    • one year ago
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    8i got your message late lol

  12. anonymous
    • one year ago
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    so is it b

  13. campbell_st
    • one year ago
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    well to find the domain, you have 2 choices... so substitute each choice n =0 into the equation and then n = 1 and see which gives the 1st term of 4

  14. campbell_st
    • one year ago
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    so does \[a_{0} = 4\times (-2)^{0 -1}\] is \[A_{0} = 4\]

  15. anonymous
    • one year ago
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    oh so it's a

  16. anonymous
    • one year ago
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    thank you

  17. anonymous
    • one year ago
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    umm it was b

  18. campbell_st
    • one year ago
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    lol... no its not a if you do the calculation its \[a_{0} = 4 \times (-2)^{-1} = 4 \times \frac{-1}{2} = -2\] all you needed to do was read the question, you were told \[a_{1} = 4 \] the 1st term was 4 so n = 1 \[a_{1} = 4 \times (-2)^{1 -1} = 4 \times (-2)^0 = 4 \times 1 =4\]

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