Answers

2015-10-09T00:20:39+08:00

This Is a Certified Answer

×
Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
 \left \{ {2x + 4y =12} \atop {3x + y = 9}} \right.

Think of a number that if you multiply it by the equation would eliminate one variable.

So in this case, I'll use the equation:
 
   3x + y = 9

What number should be multiplied by the equation above that when you combine it with 2x + 4 = 12 would eliminate one variable?

     2x + 4y =12 
   (3x + y = 9) -4 ⇒ -12x - 4y = -36
 
   2x + 4y = 12
  -12x - 4y = -36
 -----------------------
   -10x = -24
 
   -10x    -24               24                                12
  ------- = -----  ⇒   x = ----- (lowest term) ⇒ x =  ----
   -10      -10               10                                 5

(Now substitute to find y)

2x + 4y = 12

2(12/5) + 4y = 12

24/5 + 4y = 12

I want to remove the fraction part so I'll find for their lcd

(24/5 + 4y = 12) 5

24 + 20y = 60

20y     36           36              9
-----  = ---- ⇒ y = -----  ⇒ y = -----
20       20           20              5

CHECK:

3x + y = 9

3(12/5) + 9/5 = 9

36/5 + 9/5 = 9

45/5 = 9

9 = 9         

Check the attachment below =) 
1 1 1
Lovely :-) The only link missing is the graph. Everyone, rest your case. This is how this problem is solved. How can I vote 5-star? :-) :-) :-)
Omg really??? HAHA thank you so much po :)))