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(x/2)+(y/3)=-1

(x/2)+2y=4

Can someone please explain how to get the solutions set. What do I start with? Where do the numbers come from and why?

Please and Thank you!

 Jan 8, 2015

Best Answer 

 #1
avatar+23254 
+5

First, I would get rid of fractions:

---   multiply the first equation by 6:   6(x/2) + 6(y/3)  =  6(-1)   --->   3x + 2y  =  -6

---   multiply the second equation by 2:   2(x/2) + 2(2y)  =  2(4)   --->   x + 4y  =  8

Now, combine these:  3x + 2y  =  6

                                      x + 4y  =  8

If you want to eliminate the x-terms, leave the top equation alone and multiply the bottom equation by -3:

3x + 2y  =  -6   --->                                        3x + 2y  =  -6

  x + 4y  =   8   --->   multiply by -3   --->   -3x - 12y  =  -24

Add down the columns:                                      -10y  =  -30

                                                                                 y  =  3

Substitue this value back into an original equation:  x + 4y  =  8   --->   x + 4(3)  =  8   --->   x + 12  = 8

                                                                        --->   x  =  -4

 Jan 8, 2015
 #1
avatar+23254 
+5
Best Answer

First, I would get rid of fractions:

---   multiply the first equation by 6:   6(x/2) + 6(y/3)  =  6(-1)   --->   3x + 2y  =  -6

---   multiply the second equation by 2:   2(x/2) + 2(2y)  =  2(4)   --->   x + 4y  =  8

Now, combine these:  3x + 2y  =  6

                                      x + 4y  =  8

If you want to eliminate the x-terms, leave the top equation alone and multiply the bottom equation by -3:

3x + 2y  =  -6   --->                                        3x + 2y  =  -6

  x + 4y  =   8   --->   multiply by -3   --->   -3x - 12y  =  -24

Add down the columns:                                      -10y  =  -30

                                                                                 y  =  3

Substitue this value back into an original equation:  x + 4y  =  8   --->   x + 4(3)  =  8   --->   x + 12  = 8

                                                                        --->   x  =  -4

geno3141 Jan 8, 2015

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