Need assistance changing a Mixed Expression into a Common Fraction












0












$begingroup$


My workbook says the answer to this:



$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



is:



$- frac {a^2b + 3ab^2 - 4b^3}{a - 2b}$



I am continually getting this answer though:



$frac {-a^2b - 3ab^2}{a - 2b}$



What am I doing wrong here? Is there somewhere I should be multiplying by -1?



My work:
$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



$= frac {a^2(a-2b)+ab(a-2b)-b^2(a-2b)-a^3-2b^3}{a-2b}$



$= frac {a^3-2a^2b+a^2b-2ab^2-ab^2+2b^3-a^3-2b^3}{a-2b}$



$= frac {-a^2b - 3ab^2}{a - 2b}$










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  • $begingroup$
    We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
    $endgroup$
    – pwerth
    Dec 25 '18 at 2:24
















0












$begingroup$


My workbook says the answer to this:



$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



is:



$- frac {a^2b + 3ab^2 - 4b^3}{a - 2b}$



I am continually getting this answer though:



$frac {-a^2b - 3ab^2}{a - 2b}$



What am I doing wrong here? Is there somewhere I should be multiplying by -1?



My work:
$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



$= frac {a^2(a-2b)+ab(a-2b)-b^2(a-2b)-a^3-2b^3}{a-2b}$



$= frac {a^3-2a^2b+a^2b-2ab^2-ab^2+2b^3-a^3-2b^3}{a-2b}$



$= frac {-a^2b - 3ab^2}{a - 2b}$










share|cite|improve this question











$endgroup$












  • $begingroup$
    We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
    $endgroup$
    – pwerth
    Dec 25 '18 at 2:24














0












0








0





$begingroup$


My workbook says the answer to this:



$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



is:



$- frac {a^2b + 3ab^2 - 4b^3}{a - 2b}$



I am continually getting this answer though:



$frac {-a^2b - 3ab^2}{a - 2b}$



What am I doing wrong here? Is there somewhere I should be multiplying by -1?



My work:
$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



$= frac {a^2(a-2b)+ab(a-2b)-b^2(a-2b)-a^3-2b^3}{a-2b}$



$= frac {a^3-2a^2b+a^2b-2ab^2-ab^2+2b^3-a^3-2b^3}{a-2b}$



$= frac {-a^2b - 3ab^2}{a - 2b}$










share|cite|improve this question











$endgroup$




My workbook says the answer to this:



$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



is:



$- frac {a^2b + 3ab^2 - 4b^3}{a - 2b}$



I am continually getting this answer though:



$frac {-a^2b - 3ab^2}{a - 2b}$



What am I doing wrong here? Is there somewhere I should be multiplying by -1?



My work:
$a^2 + ab - b^2 - frac {a^3 - 2b^3}{a - 2b} $



$= frac {a^2(a-2b)+ab(a-2b)-b^2(a-2b)-a^3-2b^3}{a-2b}$



$= frac {a^3-2a^2b+a^2b-2ab^2-ab^2+2b^3-a^3-2b^3}{a-2b}$



$= frac {-a^2b - 3ab^2}{a - 2b}$







algebra-precalculus fractions






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edited Dec 25 '18 at 2:39







patawa91

















asked Dec 25 '18 at 2:22









patawa91patawa91

125




125












  • $begingroup$
    We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
    $endgroup$
    – pwerth
    Dec 25 '18 at 2:24


















  • $begingroup$
    We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
    $endgroup$
    – pwerth
    Dec 25 '18 at 2:24
















$begingroup$
We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
$endgroup$
– pwerth
Dec 25 '18 at 2:24




$begingroup$
We can't know what you're doing wrong if you don't show your work. Please show how you arrived at your answer
$endgroup$
– pwerth
Dec 25 '18 at 2:24










1 Answer
1






active

oldest

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1












$begingroup$

Your mistake is at the far right of your numerator: you did not distribute the negative sign. Your answer should be (correction in red)
$$displaystylefrac{a^{2}(a-2b)+ab(a-2b)-b^{2}(a-2b)color{red}-(a^{3}-2b^{3})}{a-2b}$$






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  • $begingroup$
    Thank you @pwerth for taking the time! That was it.
    $endgroup$
    – patawa91
    Dec 25 '18 at 3:16










  • $begingroup$
    You're welcome :)
    $endgroup$
    – pwerth
    Dec 25 '18 at 3:18












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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









1












$begingroup$

Your mistake is at the far right of your numerator: you did not distribute the negative sign. Your answer should be (correction in red)
$$displaystylefrac{a^{2}(a-2b)+ab(a-2b)-b^{2}(a-2b)color{red}-(a^{3}-2b^{3})}{a-2b}$$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Thank you @pwerth for taking the time! That was it.
    $endgroup$
    – patawa91
    Dec 25 '18 at 3:16










  • $begingroup$
    You're welcome :)
    $endgroup$
    – pwerth
    Dec 25 '18 at 3:18
















1












$begingroup$

Your mistake is at the far right of your numerator: you did not distribute the negative sign. Your answer should be (correction in red)
$$displaystylefrac{a^{2}(a-2b)+ab(a-2b)-b^{2}(a-2b)color{red}-(a^{3}-2b^{3})}{a-2b}$$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    Thank you @pwerth for taking the time! That was it.
    $endgroup$
    – patawa91
    Dec 25 '18 at 3:16










  • $begingroup$
    You're welcome :)
    $endgroup$
    – pwerth
    Dec 25 '18 at 3:18














1












1








1





$begingroup$

Your mistake is at the far right of your numerator: you did not distribute the negative sign. Your answer should be (correction in red)
$$displaystylefrac{a^{2}(a-2b)+ab(a-2b)-b^{2}(a-2b)color{red}-(a^{3}-2b^{3})}{a-2b}$$






share|cite|improve this answer









$endgroup$



Your mistake is at the far right of your numerator: you did not distribute the negative sign. Your answer should be (correction in red)
$$displaystylefrac{a^{2}(a-2b)+ab(a-2b)-b^{2}(a-2b)color{red}-(a^{3}-2b^{3})}{a-2b}$$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 25 '18 at 2:49









pwerthpwerth

3,340417




3,340417












  • $begingroup$
    Thank you @pwerth for taking the time! That was it.
    $endgroup$
    – patawa91
    Dec 25 '18 at 3:16










  • $begingroup$
    You're welcome :)
    $endgroup$
    – pwerth
    Dec 25 '18 at 3:18


















  • $begingroup$
    Thank you @pwerth for taking the time! That was it.
    $endgroup$
    – patawa91
    Dec 25 '18 at 3:16










  • $begingroup$
    You're welcome :)
    $endgroup$
    – pwerth
    Dec 25 '18 at 3:18
















$begingroup$
Thank you @pwerth for taking the time! That was it.
$endgroup$
– patawa91
Dec 25 '18 at 3:16




$begingroup$
Thank you @pwerth for taking the time! That was it.
$endgroup$
– patawa91
Dec 25 '18 at 3:16












$begingroup$
You're welcome :)
$endgroup$
– pwerth
Dec 25 '18 at 3:18




$begingroup$
You're welcome :)
$endgroup$
– pwerth
Dec 25 '18 at 3:18


















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