Jackie in AR Posted February 29, 2008 Share Posted February 29, 2008 [2(a-b)] - [(a/3 + b/4) + (a/6 - 3b/4)] = The answer is 3/2(a-b) according to the book. Will someone please show me how to work this problem correctly? Thanks! Quote Link to comment Share on other sites More sharing options...
Krista in LA Posted February 29, 2008 Share Posted February 29, 2008 [2(a-b)] - [(a/3 + b/4) + (a/6 - 3b/4)] = The answer is 3/2(a-b) according to the book. Will someone please show me how to work this problem correctly? Thanks! The lowest common demonitator for 3, 4, and 6 is 12 so you need to multiply each fraction to get it over 12. (12/12)* [2(a-b)] - {[(4/4)(a/3) + (3/3)(b/4)] + [(2/2)(a/6) - (3/3)(3b/4)]} = 24(a-b)/12 - [(4a/12) + (3b/12) + 2a/12 - 9b/12)] = (24a-24b)/12 - [(6a-6b)/12] = (18a-18b)/12 = 18(a-b)/12 = 3(a-b)/2 = 3/2 (a-b) Quote Link to comment Share on other sites More sharing options...
Snickerdoodle Posted February 29, 2008 Share Posted February 29, 2008 :) Quote Link to comment Share on other sites More sharing options...
Kat in GA Posted February 29, 2008 Share Posted February 29, 2008 [2(a-b)] - [(a/3 + b/4) + (a/6 - 3b/4)] = The answer is 3/2(a-b) according to the book. Will someone please show me how to work this problem correctly? Thanks! Here is a slight variation on the other answer: First get rid of the brackets: 2a - 2b - a/3 - b/4 - a/6 + 3b/4 Change all the a's to sixths and all the b's to fourths: 12a/6 - 8b/4 - 2a/6 - b/4 - a/6 + 3b/4 = 9a/6 - 6b/4 Then you reduce: 3a/2 - 3b/2 = 3/2 (a - b) Quote Link to comment Share on other sites More sharing options...
JenneinCA Posted February 29, 2008 Share Posted February 29, 2008 [2(a-b)] - [(a/3 + b/4) + (a/6 - 3b/4)] = distributing the 2 and the negative: 2a-2b -a/3 -b/4 -a/6 +3b/4 = Common denominator of 12: 24a/12 -24b/12 -4a/12 -3b/12 -2a/12 +9b/12 Reorder to put like terms together: 24a/12 -4a/12 -2a/12 -24b/12 -3b/12 +9b/12 Combine like terms: (24a-4a-2a)/12 + (-24b-3b+9b)/12 More combining: 18a/12 + (-18b)/12 Simplifying: 3a/2 -3b/2 More simplifying: (3a-3b)/2 Still more: (3/2)(a-b) Quote Link to comment Share on other sites More sharing options...
Jackie in AR Posted February 29, 2008 Author Share Posted February 29, 2008 Here is what I did wrong: I multiplied each term by 12 instead of 12/12 as I should have. And when I divide the answer I came up with (18a-18b) by 12, I get 3/2 (a-b). Many thanks to all of you!! Quote Link to comment Share on other sites More sharing options...
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