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anonymous

  • one year ago

Can anyone help me with this pre-cal please.

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  1. anonymous
    • one year ago
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  2. anonymous
    • one year ago
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    What's the question?

  3. anonymous
    • one year ago
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    It's in the attachment

  4. anonymous
    • one year ago
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    Which one(s) are you having trouble with?

  5. anonymous
    • one year ago
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    All of them, but any help would be great.

  6. anonymous
    • one year ago
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    So, the first one is: a. Evaluate the expression 2a−3b/2 when a = −5 and b = −3 This means to plug the given values into the expression, and simplify. According to order of operations, the division gets done *before* the subtraction, so the expression (when typeset) looks like this: \[ 2a - \frac{3b}{2}\] Now, what do you get when you plug in -5 for a and -3 for b?

  7. anonymous
    • one year ago
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    |dw:1442606735382:dw| That's how it looks, and I plugged in a and b on the 2nd one

  8. anonymous
    • one year ago
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    Okay, that's a different problem. So, we need to figure out which is the problem they're asking! What you had written was 2a - 3b/2, which is \[2a - \frac{3b}{2}\] What you put in your posted image is (2a-3b)/2, which is \[\frac{2a-3b}{2}\] They're different, and they'll give different answers.

  9. anonymous
    • one year ago
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    Oh okay, I didn't know that. It's the second one then, (2a-3b)/2

  10. anonymous
    • one year ago
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    Then you're off to a good start! Just start simplifying the numerator in \[\frac{2(-5) - 3(-3)}{2}\] ... what do you get?

  11. anonymous
    • one year ago
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    |dw:1442607214084:dw| Is that right?

  12. anonymous
    • one year ago
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    You got it! Good! Done with the first one!

  13. anonymous
    • one year ago
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    Awesome

  14. anonymous
    • one year ago
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    Do you have an image for the second one? I suspect what appears in my attachment isn't the actual problem you want...

  15. anonymous
    • one year ago
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    No, that's the actual problem, it's that exactly :)

  16. anonymous
    • one year ago
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    Okay, then question (1b) is: Simplify: 8y − 15 − 3(7 − y) When you put this in regular math style, it looks like this: \[ 8y - 15 - 3(7-y)\] You need to do the multiplication first, so multiply out that last part, -3(7-y). What does that give you?

  17. anonymous
    • one year ago
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    -15.89? or -21? If I did it right

  18. anonymous
    • one year ago
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    We're on a different problem now ... there's no longer any a = -5 or b = -3 in sight! (That was just for problem 1a.) Now, just multiply this out: \[-3(7-y)\] Your answer will have a "y" in it!

  19. anonymous
    • one year ago
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    -15.89y?

  20. anonymous
    • one year ago
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    You need to use a distributive law: a(b+c) = ab + ac Think: What's -3 times 7? (write it down) Then think: what's -3 times -y? (write it down)

  21. anonymous
    • one year ago
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    I'm curious .... where did you get the -15.89y from?

  22. anonymous
    • one year ago
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    -3 times 7 is -21 -3 times -y is 5.10 I got -15.89 by putting -3(7-y) directly into the calculator... which is why I thought it was wrong

  23. anonymous
    • one year ago
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    There's no NUMBER being plugged in for y in this problem. -3 times -y is just 3y . (Remember: a negative times a negative is positive) This problem isn't a calculator problem; it's an algebra problem (working with variables).

  24. anonymous
    • one year ago
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    Ohh, okay. I was confused about that

  25. anonymous
    • one year ago
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    Here's where we are so far: \[\begin{align} 8y−15−3(7−y) &= 8y - 15 - 21 + 3y \cr &= \text{ ??} \end{align}\] Now, you want to combine like terms. (Combine the number parts; combine the y terms.) What do you get?

  26. anonymous
    • one year ago
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    Sorry my OpenStudy is acting up and being really slow. Yes, 11y-33?

  27. anonymous
    • one year ago
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    My computer just locked up! I had to close my whole browser and re-open and come back here? Might have been something going on at OpenStudy. I like the 11y part. What's -15 - 21?

  28. anonymous
    • one year ago
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    Oh, it's 36 then plus 3 is 39?

  29. anonymous
    • one year ago
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    Unless it's negative 15 then it's 6 plus 3 which is 9

  30. anonymous
    • one year ago
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    Remember: -15 - 21 means (-15) + (-21). Move to the left 15; move to the left 21 more; where do you end up? (You were *close* before when you got -33; just goofed up the arithmetic a bit.)

  31. anonymous
    • one year ago
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    36

  32. anonymous
    • one year ago
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    with a minus sign in front: -15 - 21 = -36. Now, put it all together: \[ 8y−15−3(7−y) = 8y−15−21+3y = 11y - 36\] and that's it!

  33. anonymous
    • one year ago
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    Oh okay, got it! :) I added an extra 3 in my problem that's why I kept saying "plus 3" and yea, I forgot my minus sign. Thank you.

  34. anonymous
    • one year ago
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    I'm just kind of having fun here today; I visited this site a few years ago, and didn't even know if it still existed. Clearly it does! It seems like a great resource for the math community. I may try to make regular appearances here! I've been working on a Precalculus course for years now, and I'm more than 2/3 of the way done: http://www.onemathematicalcat.org/Math/Precalculus_obj/tableOfContentsPreCalculus.htm Lots of the stuff I was helping you with today is from my Algebra course (they always do algebra review in PreCalc): http://www.onemathematicalcat.org/algebra_book/online_problems/table_of_contents.htm You might want to check them out to see if they can help you. There's lots and lots of lots of practice with immediate feedback, so you can check your answers. Well, I'd really love to stay and help you more right now, but I've got some other things I've got to do. Just re-post these as separate questions, and I'm sure someone will help you quickly! Have a wonderful day!

  35. anonymous
    • one year ago
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    Okay, well thank you sooo much! You have a good day too!

  36. anonymous
    • one year ago
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    Thanks! Bye!

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