Stuck on $6y-3-(2y-1)=12$











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Solve for y:



$$6y-3-(2y-1)=12tag1$$



$$6y-3-2y-1=12tag2$$



$$4y-4=12tag3$$



$$4y=12+4tag4$$



$$y=4tag5$$



But when I plugged into $(1)$ it is wrong,



$y=4$
$$6y-3-(2y-1)=12tag1$$



$$24-3-(8-1)=12tag a$$



$$24-3-(7)=12tag b$$



$$14=12tag c$$



Where it is wrong?










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  • 3




    $-(2y - 1) = -2y + 1$.
    – T. Bongers
    Nov 13 at 22:24












  • Eq (2) is wrong.
    – user376343
    Nov 13 at 22:26






  • 6




    Great question. The demonstrated effort is great. Double check everything carefully.
    – The Count
    Nov 13 at 22:26















up vote
5
down vote

favorite












Solve for y:



$$6y-3-(2y-1)=12tag1$$



$$6y-3-2y-1=12tag2$$



$$4y-4=12tag3$$



$$4y=12+4tag4$$



$$y=4tag5$$



But when I plugged into $(1)$ it is wrong,



$y=4$
$$6y-3-(2y-1)=12tag1$$



$$24-3-(8-1)=12tag a$$



$$24-3-(7)=12tag b$$



$$14=12tag c$$



Where it is wrong?










share|cite|improve this question




















  • 3




    $-(2y - 1) = -2y + 1$.
    – T. Bongers
    Nov 13 at 22:24












  • Eq (2) is wrong.
    – user376343
    Nov 13 at 22:26






  • 6




    Great question. The demonstrated effort is great. Double check everything carefully.
    – The Count
    Nov 13 at 22:26













up vote
5
down vote

favorite









up vote
5
down vote

favorite











Solve for y:



$$6y-3-(2y-1)=12tag1$$



$$6y-3-2y-1=12tag2$$



$$4y-4=12tag3$$



$$4y=12+4tag4$$



$$y=4tag5$$



But when I plugged into $(1)$ it is wrong,



$y=4$
$$6y-3-(2y-1)=12tag1$$



$$24-3-(8-1)=12tag a$$



$$24-3-(7)=12tag b$$



$$14=12tag c$$



Where it is wrong?










share|cite|improve this question















Solve for y:



$$6y-3-(2y-1)=12tag1$$



$$6y-3-2y-1=12tag2$$



$$4y-4=12tag3$$



$$4y=12+4tag4$$



$$y=4tag5$$



But when I plugged into $(1)$ it is wrong,



$y=4$
$$6y-3-(2y-1)=12tag1$$



$$24-3-(8-1)=12tag a$$



$$24-3-(7)=12tag b$$



$$14=12tag c$$



Where it is wrong?







algebra-precalculus






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share|cite|improve this question













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edited Nov 13 at 22:24

























asked Nov 13 at 22:23









user583851

1




1








  • 3




    $-(2y - 1) = -2y + 1$.
    – T. Bongers
    Nov 13 at 22:24












  • Eq (2) is wrong.
    – user376343
    Nov 13 at 22:26






  • 6




    Great question. The demonstrated effort is great. Double check everything carefully.
    – The Count
    Nov 13 at 22:26














  • 3




    $-(2y - 1) = -2y + 1$.
    – T. Bongers
    Nov 13 at 22:24












  • Eq (2) is wrong.
    – user376343
    Nov 13 at 22:26






  • 6




    Great question. The demonstrated effort is great. Double check everything carefully.
    – The Count
    Nov 13 at 22:26








3




3




$-(2y - 1) = -2y + 1$.
– T. Bongers
Nov 13 at 22:24






$-(2y - 1) = -2y + 1$.
– T. Bongers
Nov 13 at 22:24














Eq (2) is wrong.
– user376343
Nov 13 at 22:26




Eq (2) is wrong.
– user376343
Nov 13 at 22:26




6




6




Great question. The demonstrated effort is great. Double check everything carefully.
– The Count
Nov 13 at 22:26




Great question. The demonstrated effort is great. Double check everything carefully.
– The Count
Nov 13 at 22:26










2 Answers
2






active

oldest

votes

















up vote
2
down vote



accepted










First of all, congratulations on realizing there must be a mistake somewhere. Others have pointed out what's wrong, so that by now it may be obvious. But for future reference, you can sometimes localize the step at which the error occurred by plugging the (incorrect) answer into some of the other equations as well; if it satisfies an intermediate equation, then you know the error occurred earlier.



In this case, $y=4$ satisfies equation (2):



$$6y-3-2y-1=12\
24-3-8-1=12\
21-8-1=12\
13-1=12\
12=12$$



This means that the error occurred in going from (1) to (2). But all you did there was to remove parentheses, which seems innocuous enough. How could anything go wrong? Ah! That minus sign in front of the parentheses! You have to distribute it!



Another thing to do is to take note of mistakes that you tend to make on a regular basis, and slow down when you recognize you're about to take a step that you know you've often done wrong. For you it might be minus signs; for me it's pointing inequality signs in the proper direction (among many other idiosyncratic mistakes). Mathematics doesn't have to be done in a hurry.






share|cite|improve this answer




























    up vote
    0
    down vote













    To ensure this has an answer, look at your leap from (1) to (2). The term $-(2y-1)$ should have been expanded as $-2y+1.$ Thus, (2) should be $$6y - 3 -2y +1 = 12.$$



    I assume you can take it from here.



    Note also that this is an excellent way to do math: left to right, top down. You should be able to retrace your steps and determine if you've made any mistakes. You should go through this with a fine comb, as the mistake may not instantly pop out.






    share|cite|improve this answer





















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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes








      up vote
      2
      down vote



      accepted










      First of all, congratulations on realizing there must be a mistake somewhere. Others have pointed out what's wrong, so that by now it may be obvious. But for future reference, you can sometimes localize the step at which the error occurred by plugging the (incorrect) answer into some of the other equations as well; if it satisfies an intermediate equation, then you know the error occurred earlier.



      In this case, $y=4$ satisfies equation (2):



      $$6y-3-2y-1=12\
      24-3-8-1=12\
      21-8-1=12\
      13-1=12\
      12=12$$



      This means that the error occurred in going from (1) to (2). But all you did there was to remove parentheses, which seems innocuous enough. How could anything go wrong? Ah! That minus sign in front of the parentheses! You have to distribute it!



      Another thing to do is to take note of mistakes that you tend to make on a regular basis, and slow down when you recognize you're about to take a step that you know you've often done wrong. For you it might be minus signs; for me it's pointing inequality signs in the proper direction (among many other idiosyncratic mistakes). Mathematics doesn't have to be done in a hurry.






      share|cite|improve this answer

























        up vote
        2
        down vote



        accepted










        First of all, congratulations on realizing there must be a mistake somewhere. Others have pointed out what's wrong, so that by now it may be obvious. But for future reference, you can sometimes localize the step at which the error occurred by plugging the (incorrect) answer into some of the other equations as well; if it satisfies an intermediate equation, then you know the error occurred earlier.



        In this case, $y=4$ satisfies equation (2):



        $$6y-3-2y-1=12\
        24-3-8-1=12\
        21-8-1=12\
        13-1=12\
        12=12$$



        This means that the error occurred in going from (1) to (2). But all you did there was to remove parentheses, which seems innocuous enough. How could anything go wrong? Ah! That minus sign in front of the parentheses! You have to distribute it!



        Another thing to do is to take note of mistakes that you tend to make on a regular basis, and slow down when you recognize you're about to take a step that you know you've often done wrong. For you it might be minus signs; for me it's pointing inequality signs in the proper direction (among many other idiosyncratic mistakes). Mathematics doesn't have to be done in a hurry.






        share|cite|improve this answer























          up vote
          2
          down vote



          accepted







          up vote
          2
          down vote



          accepted






          First of all, congratulations on realizing there must be a mistake somewhere. Others have pointed out what's wrong, so that by now it may be obvious. But for future reference, you can sometimes localize the step at which the error occurred by plugging the (incorrect) answer into some of the other equations as well; if it satisfies an intermediate equation, then you know the error occurred earlier.



          In this case, $y=4$ satisfies equation (2):



          $$6y-3-2y-1=12\
          24-3-8-1=12\
          21-8-1=12\
          13-1=12\
          12=12$$



          This means that the error occurred in going from (1) to (2). But all you did there was to remove parentheses, which seems innocuous enough. How could anything go wrong? Ah! That minus sign in front of the parentheses! You have to distribute it!



          Another thing to do is to take note of mistakes that you tend to make on a regular basis, and slow down when you recognize you're about to take a step that you know you've often done wrong. For you it might be minus signs; for me it's pointing inequality signs in the proper direction (among many other idiosyncratic mistakes). Mathematics doesn't have to be done in a hurry.






          share|cite|improve this answer












          First of all, congratulations on realizing there must be a mistake somewhere. Others have pointed out what's wrong, so that by now it may be obvious. But for future reference, you can sometimes localize the step at which the error occurred by plugging the (incorrect) answer into some of the other equations as well; if it satisfies an intermediate equation, then you know the error occurred earlier.



          In this case, $y=4$ satisfies equation (2):



          $$6y-3-2y-1=12\
          24-3-8-1=12\
          21-8-1=12\
          13-1=12\
          12=12$$



          This means that the error occurred in going from (1) to (2). But all you did there was to remove parentheses, which seems innocuous enough. How could anything go wrong? Ah! That minus sign in front of the parentheses! You have to distribute it!



          Another thing to do is to take note of mistakes that you tend to make on a regular basis, and slow down when you recognize you're about to take a step that you know you've often done wrong. For you it might be minus signs; for me it's pointing inequality signs in the proper direction (among many other idiosyncratic mistakes). Mathematics doesn't have to be done in a hurry.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Nov 13 at 23:08









          Barry Cipra

          58k652121




          58k652121






















              up vote
              0
              down vote













              To ensure this has an answer, look at your leap from (1) to (2). The term $-(2y-1)$ should have been expanded as $-2y+1.$ Thus, (2) should be $$6y - 3 -2y +1 = 12.$$



              I assume you can take it from here.



              Note also that this is an excellent way to do math: left to right, top down. You should be able to retrace your steps and determine if you've made any mistakes. You should go through this with a fine comb, as the mistake may not instantly pop out.






              share|cite|improve this answer

























                up vote
                0
                down vote













                To ensure this has an answer, look at your leap from (1) to (2). The term $-(2y-1)$ should have been expanded as $-2y+1.$ Thus, (2) should be $$6y - 3 -2y +1 = 12.$$



                I assume you can take it from here.



                Note also that this is an excellent way to do math: left to right, top down. You should be able to retrace your steps and determine if you've made any mistakes. You should go through this with a fine comb, as the mistake may not instantly pop out.






                share|cite|improve this answer























                  up vote
                  0
                  down vote










                  up vote
                  0
                  down vote









                  To ensure this has an answer, look at your leap from (1) to (2). The term $-(2y-1)$ should have been expanded as $-2y+1.$ Thus, (2) should be $$6y - 3 -2y +1 = 12.$$



                  I assume you can take it from here.



                  Note also that this is an excellent way to do math: left to right, top down. You should be able to retrace your steps and determine if you've made any mistakes. You should go through this with a fine comb, as the mistake may not instantly pop out.






                  share|cite|improve this answer












                  To ensure this has an answer, look at your leap from (1) to (2). The term $-(2y-1)$ should have been expanded as $-2y+1.$ Thus, (2) should be $$6y - 3 -2y +1 = 12.$$



                  I assume you can take it from here.



                  Note also that this is an excellent way to do math: left to right, top down. You should be able to retrace your steps and determine if you've made any mistakes. You should go through this with a fine comb, as the mistake may not instantly pop out.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered Nov 13 at 22:31









                  Sean Roberson

                  6,30331327




                  6,30331327






























                       

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