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lalaland_lauren

  • one year ago

Select the polynomial that is a perfect square trinomial. 49x2 − 8x + 16 4a2 − 10a + 25 25b2 − 5b + 10 16x2 − 8x + 1

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  1. lalaland_lauren
    • one year ago
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    please help :(

  2. JoannaBlackwelder
    • one year ago
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    Have you tried factoring? Or the pythaorgean theorem?

  3. lalaland_lauren
    • one year ago
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    I would, but I struggle with this kind of stuff and I need help to understand it

  4. JoannaBlackwelder
    • one year ago
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    Ok, for perfect square it has to factor to the form (ax + b)^2, so we can try factoring with the same numbers in each of the binomials.

  5. JoannaBlackwelder
    • one year ago
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    |dw:1437761715779:dw| I chose 7 because 7*7 is 49

  6. JoannaBlackwelder
    • one year ago
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    And -4 because -4*-4=16 and the middle number is negative.

  7. JoannaBlackwelder
    • one year ago
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    Does that make sense so far?

  8. lalaland_lauren
    • one year ago
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    Yup

  9. lalaland_lauren
    • one year ago
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    So that's a perfect square?

  10. JoannaBlackwelder
    • one year ago
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    |dw:1437761833427:dw| We don't know yet. We need to check it and see if it gets us back to the original function.

  11. JoannaBlackwelder
    • one year ago
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    Is that the same as A?

  12. lalaland_lauren
    • one year ago
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    No :P

  13. JoannaBlackwelder
    • one year ago
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    Ok, then that is not it. Can you try to do the same thing with B?

  14. lalaland_lauren
    • one year ago
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    I don't think it is because I end up with 2a+5 and there's a negative in the middle, so no right?

  15. JoannaBlackwelder
    • one year ago
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    Well, since there is a negative in the middle, we need to use -5 (2a-5)(2a-5)

  16. JoannaBlackwelder
    • one year ago
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    But does that multiply back out to give us what we started with?

  17. lalaland_lauren
    • one year ago
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    no, it'd be 4a^2-20a+25

  18. JoannaBlackwelder
    • one year ago
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    Right, so that's not it. What about C?

  19. lalaland_lauren
    • one year ago
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    I can't find the square root of ten so I don't think it's a perfect square

  20. JoannaBlackwelder
    • one year ago
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    Yeah, 10 doesn't have a perfect square, but we could:|dw:1437762288347:dw|

  21. JoannaBlackwelder
    • one year ago
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    But you are right, that wouldn't be the answer. :-)

  22. JoannaBlackwelder
    • one year ago
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    Let's check D.

  23. lalaland_lauren
    • one year ago
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    4x+1 is what I got

  24. JoannaBlackwelder
    • one year ago
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    Since the middle number is negative, we need to use -1

  25. JoannaBlackwelder
    • one year ago
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    Can you try multiplying out (4x-1)(4x-1)?

  26. lalaland_lauren
    • one year ago
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    I got 16x^2-8x+1 :-)

  27. JoannaBlackwelder
    • one year ago
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    Yay! :-D

  28. lalaland_lauren
    • one year ago
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    Thank you for helping, I got a 100%!! ^-^

  29. JoannaBlackwelder
    • one year ago
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    Awesome! You`re welcome!

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