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anonymous

  • one year ago

Please help for medal- its extra credit. Let f(x) = -5x - 4 and g(x) = 6x - 7. Find f(x) + g(x) A. x - 11 B. -11x - 11 C. x + 3 D. -11x = 3b

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  1. freckles
    • one year ago
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    (-5+6)x=? -4-7=?

  2. jim_thompson5910
    • one year ago
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    \[\Large {\color{red}{f(x) = -5x-4}}\] \[\Large {\color{blue}{g(x) = 6x-7}}\] -------------------------------- \[\Large {\color{red}{f(x)}} + {\color{blue}{g(x)}} = ({\color{red}{-5x-4}})+({\color{blue}{6x-7}})\] \[\Large f(x) + g(x) = -5x-4 + 6x - 7\] \[\Large f(x) + g(x) = ???\]

  3. anonymous
    • one year ago
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    x-11

  4. jim_thompson5910
    • one year ago
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    correct

  5. anonymous
    • one year ago
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    Can you help with another one? I dont understand the whole domain part... Let f(x) = 3x + 2 and g(x) =7x + 6. Find f ·g and its domain. A. 6x2 + 4x + 42; all real numbers B. 21x2 + 32x + 12; all real numbers C. 21x2 +32x + 12; all real numbers except x = -6/7 D. 6x2 + 4x + 42; all real numbers except x = -2/3 I know it's 21x^2+32x +12

  6. anonymous
    • one year ago
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    @jim_thompson5910

  7. jim_thompson5910
    • one year ago
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    f * g means f(x) times g(x) so you have to expand out (3x+2)*(7x+6) you can use the FOIL rule or a table like this one |dw:1436827943285:dw|

  8. anonymous
    • one year ago
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    yes, I know what f(x)*g(x) is = 21x^2+32x +12 But what does it mean by find the domain? How do I find it and figure out if its all real numbers or not?

  9. anonymous
    • one year ago
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    Thank you for the help (:

  10. jim_thompson5910
    • one year ago
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    the domain of f(x) and g(x) is the set of all real numbers. You can plug in any number for x without worrying about things like division by zero, taking the square root of a negative number, etc etc. The same applies to f(x)*g(x). Multiplying any two polynomials gives you a polynomial. The domain of any polynomial is the set of all real numbers

  11. jim_thompson5910
    • one year ago
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    saying something like `all real numbers except x = -6/7` is false because x = -6/7 is perfectly valid as an input. Go ahead and try it

  12. anonymous
    • one year ago
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    I thought so! but what about f/g? f(x) = x2 - 16 and g(x) = x+4. Find and its domain. A. x - 4; all real numbers except x not equal 4 B. x + 4; all real numbers except x not equal -4 C. x + 4; all real numbers except x not equal 4 D. x - 4; all real numbers except x not equal -4; I know its Either A or D

  13. anonymous
    • one year ago
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    |dw:1436828284091:dw|

  14. jim_thompson5910
    • one year ago
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    hint: you cannot divide by zero, so make sure that the denominator x+4 is not zero

  15. anonymous
    • one year ago
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    I don't quite understand..

  16. jim_thompson5910
    • one year ago
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    solve x+4 = 0 for x to figure out what restriction you have to make

  17. anonymous
    • one year ago
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    obviously it's -4 for x but what do you mean by restriction? I'm sorry I'm stuck.. I'm good with working through equations but this doesn't make sense to me

  18. jim_thompson5910
    • one year ago
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    well if x = -4, then the denominator x+4 becomes 0 right?

  19. anonymous
    • one year ago
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    Can you draw it out or something? How do you determine that?

  20. anonymous
    • one year ago
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    I'm sorry

  21. jim_thompson5910
    • one year ago
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    The expression simplifies to x-4 The only restriction is that \(\Large x \ne -4\) to avoid making the denominator 0. Any other x value works

  22. anonymous
    • one year ago
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    ohh I understand now!! Thanks!

  23. anonymous
    • one year ago
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    So it was A?

  24. jim_thompson5910
    • one year ago
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    no, I said x cannot equal -4 (not positive 4)

  25. anonymous
    • one year ago
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    oops my bad!

  26. Setsuna-Yuregeshi
    • one year ago
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    @jim_thompson5910, how did you get the red and blue colors in your first posts?

  27. jim_thompson5910
    • one year ago
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    if you right click on the LaTex math, you can go to the "show math as" and then to "Tex commands"

  28. jim_thompson5910
    • one year ago
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    strangely, it's not working for me. Idk if it's working for you but it should show you this \Large {\color{red}{f(x)}} + {\color{blue}{g(x)}} = ({\color{red}{-5x-4}})+({\color{blue}{6x-7}})

  29. jim_thompson5910
    • one year ago
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    surround `\Large {\color{red}{f(x)}} + {\color{blue}{g(x)}} = ({\color{red}{-5x-4}})+({\color{blue}{6x-7}})` with `\[` and `\]` to see the LaTex formatting show up

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