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anonymous

  • one year ago

Fan and medal*** If (8z − 9)(8z + 9) = az^2 − b, what is the value of a? The value of a is____

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  1. jtvatsim
    • one year ago
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    Probably as a first step you should multiply the two parentheses on the left. That may help you get started on the problem. Are you comfortable with doing that?

  2. anonymous
    • one year ago
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    yes, let me multiply

  3. jtvatsim
    • one year ago
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    Alright, sounds good. :)

  4. anonymous
    • one year ago
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    64z^2- 81 I don't know if I did right

  5. jtvatsim
    • one year ago
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    You did it perfectly! Nice job

  6. jtvatsim
    • one year ago
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    Now look closely at the two equations they gave you 64z^2 - 81 = az^2 - b notice that they both "look" the same. They both have a z^2 term. They both have a subtraction. And they both have "something" in front of the z^2 term.

  7. anonymous
    • one year ago
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    yes,i see so what I need to do now?

  8. jtvatsim
    • one year ago
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    Well, we can simply look and visually see that "a" must be 64. There is no other way that these two equations can be equal. In fact, for a bonus, I can also see that "b" must be 81.

  9. jtvatsim
    • one year ago
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    Mathematicians call this "having the same form." We were able to take the parentheses and transform them into an equation that had the same form as the equation on the right. Then, solving the problem is easy and we can trust our intuition.

  10. jtvatsim
    • one year ago
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    It's a little bit of a stretch to see it. So let me know if you have any questions. :)

  11. anonymous
    • one year ago
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    so wait, its the answer its 81

  12. jtvatsim
    • one year ago
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    Not quite. They want to know what the value of "a" is. "a" must be 64. I threw in the part about b as a bonus just so you could see that as well.

  13. jtvatsim
    • one year ago
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    Basically, the question just wants you to answer "What is the number in front of the z^2?" Instead of keeping it simple, though, they tried to get fancy by setting equations equal. It's the same thing though.

  14. anonymous
    • one year ago
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    yea I see can you check my answer for a different question please I already have the answer I just want to check

  15. jtvatsim
    • one year ago
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    go ahead! :)

  16. anonymous
    • one year ago
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    Choose the correct simplification of 7x^2(6x + 3x^2 − 4). my answer: 21x^4 + 42x^3 - 28x^2

  17. jtvatsim
    • one year ago
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    Yep looks good. They tried to trick you be playing the 3x^2 in the middle, but looks like you got it. And you kept all the signs straight. Nice!

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