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anonymous

  • 4 years ago

if x=.28 determine the three real solutions (zeros) of F(X)=x^5-7x^4+10x^3+14x^2-21x

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  1. anonymous
    • 4 years ago
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    What does it mean by if x=0.28?

  2. anonymous
    • 4 years ago
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    it's a function and .28 has to be plugged in where there is an X

  3. anonymous
    • 4 years ago
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    Okay x^5-7x^4+10x^3+14x^2-21x=0 x(x^4-7x^3+10x^2+14x-21)=0 So one solution is x=0. If we divide through by x we are left with x^4-7x^3+10x^2+14x-21=0 which has two complex solutions and two real ones.

  4. anonymous
    • 4 years ago
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    i did not get the last part???

  5. anonymous
    • 4 years ago
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    I just took the x to the other side so I would be left with x^4-7x^3+10x^2+14x-21=0 I check wolfram and the are two real solutions and two complex one. http://www.wolframalpha.com/input/?i=x^5-7x^4%2B10x^3%2B14x^2-21x These other solutions we can estimate but not find exact answers.

  6. anonymous
    • 4 years ago
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    What grade/ level are you in?

  7. anonymous
    • 4 years ago
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    i am in high school senior year

  8. anonymous
    • 4 years ago
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    Okay good, one way we can estimate is by graphing it on your graphics calculator and have it estimate the other two solutions. Another way is to write it up in a program and use Newton's Method or another root finding tool.

  9. anonymous
    • 4 years ago
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    yeah i have a graphing calc so how would i do it? if u can help me!!! please

  10. anonymous
    • 4 years ago
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    Okay first off we need to graph y=x^5-7x^4+10x^3+14x^2-21x, are you able to do this? What model/brand is your graphics calculator?

  11. anonymous
    • 4 years ago
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    ok hold on

  12. anonymous
    • 4 years ago
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    TI-84 texas

  13. anonymous
    • 4 years ago
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    okay i graphed it

  14. anonymous
    • 4 years ago
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    Good, that's the calculator I had in high school too. Makes this easier.

  15. anonymous
    • 4 years ago
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    ok

  16. anonymous
    • 4 years ago
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    so what do i do now?

  17. anonymous
    • 4 years ago
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    Now press 2nd Trace

  18. anonymous
    • 4 years ago
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    ok

  19. anonymous
    • 4 years ago
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    I don't have the calculator anymore, but there should be some option called zeros or roots. Choose that option

  20. anonymous
    • 4 years ago
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    ok

  21. anonymous
    • 4 years ago
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    it says lef bound? right bound?

  22. anonymous
    • 4 years ago
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    good, now for the left bound you want to choose the closest point you can get before the graph crosses the x axis for the right bound you want to get it as close to x axis after you've crossed it.

  23. anonymous
    • 4 years ago
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    Remeber you have to do this step for each point the graph crosses the x-axis. So for your function you need to do this 3 times to get all the real roots.

  24. anonymous
    • 4 years ago
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    ok

  25. anonymous
    • 4 years ago
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    What answers are you getting?

  26. anonymous
    • 4 years ago
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    -1.36823 and 1.18796

  27. anonymous
    • 4 years ago
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    Good work, that's correct. :D

  28. anonymous
    • 4 years ago
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    yay thanks to u

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