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anonymous

  • one year ago

Marvin was completing the square, and his work is shown below. Identify the line where he made his mistake. f(x) = 2x^2 − 8x + 5 Line 1: f(x) = 2(x^2 − 8x) + 5 Line 2: f(x) = 2(x^2 − 8x + 16) + 5 − 32 Line 3: f(x) = 2(x − 4)^2 − 27 Line 1 Line 2 Line 3 He did not make any mistakes I think line 2, amirite?

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  1. anonymous
    • one year ago
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    yes, he didn't factor the 2 out correctly

  2. dinamix
    • one year ago
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    f(x) =2x^2-16x+5 this equation i think the answer is line 3

  3. anonymous
    • one year ago
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    oh wait, sorry. That factoring mistake is on line 1, not 2.

  4. dinamix
    • one year ago
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    yup this @peachpi and he didnt right the correct must will f(x) = 2x^2-16x+5 and the aswer line 3

  5. dinamix
    • one year ago
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    2(x^2-4) @peachpi

  6. anonymous
    • one year ago
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    Y'all lost me

  7. anonymous
    • one year ago
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    \(2x^2-8x\) = \(2(x^2-4x)\) is what I meant

  8. anonymous
    • one year ago
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    they're asking you to find the mistake. The mistake is that the factoring on line 1 was wrong.

  9. dinamix
    • one year ago
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    all lines is wrong @peachpi

  10. anonymous
    • one year ago
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    yes, they're all wrong. But the mistake first happened on line 1

  11. anonymous
    • one year ago
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    Oh, alright, I see where you guys are coming from

  12. dinamix
    • one year ago
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    i think he made mistake in f(x) = 2x^2-8x+5 and should be 2x^2-16x+5 peachpi

  13. dinamix
    • one year ago
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    and the lines will be all correct

  14. dinamix
    • one year ago
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    did understand me @peachpi

  15. anonymous
    • one year ago
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    No. I don't know where you're getting that. The two expressions you typed aren't equal. This problem is about completing the square, which is basically rewriting the same thing in another way. You can't just change -8x to -16x because it changes the value of the expression.

  16. dinamix
    • one year ago
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    yup he did write it correct thats problem

  17. dinamix
    • one year ago
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    u didnt understand me if the function f(x) = 2x^2-16x+5 we all lines correct right ?

  18. dinamix
    • one year ago
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    find*

  19. anonymous
    • one year ago
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    No, because changing -8 to -16 changes the function. This is the correct solution to the problem, with no mistakes \(f(x)=2x^2-8x+5\) \(f(x)=2(x^2-4x)+5\) \(f(x)=2(x^2-4x+4)+5-8\) \(f(x)=2(x-2)^2-3\)

  20. anonymous
    • one year ago
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    Is he getting confused with the actual function? Hes really confusing me

  21. anonymous
    • one year ago
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    yeah I think so. If you compare what I have with the solution in the problem statement, you can see the mistake on the first line

  22. anonymous
    • one year ago
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    He didn't divide the 8x by the 2 you're factoring?

  23. dinamix
    • one year ago
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    @gigirained are really this function f(x) = 2x^2-8x+5 are u sure its -8x not -16x ?

  24. anonymous
    • one year ago
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    yes correct @gigirained

  25. anonymous
    • one year ago
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    Positive its -8x

  26. anonymous
    • one year ago
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    @dinamix I see what you're doing. The objective of the problem is to find the mistake, if there is one. You're finding a function that matches the steps provided. So yeah if the initial function had -16x, then the work would be correct.

  27. dinamix
    • one year ago
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    ok he did mistake , didnt divide 8x by 2

  28. dinamix
    • one year ago
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    yup @peachpi this why i check if write function correct or no

  29. anonymous
    • one year ago
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    Thanks you guys, @peachpi and @dinamix

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