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how do we find k1 and k2 in the following example: 16= 2k1 + 3k2 & 25= 5k1+4k2

 Mar 18, 2015

Best Answer 

 #1
avatar+130516 
+5

16= 2k1 + 3k2

25= 5k1 + 4k2      

Multiply the first equation by 4 and the second equation by -3.....this will eliminate k2.....so we have

64 =    8k1     + 12k2

-75 = -15k1    -  12k2       add these together

-11 = -7k1      divide by -7 on both sides

11/7  = k1      substitute  this into either equation to find k2  ...I'll use the first one

16 = 2(11/7) + 3k2

16= 22/7 + 3k2      subtract 22/7 from borh sides

16 - 22/7  = 3k2

[112 - 22]/7  = 3k2

90/7  = 3k2     divide by 3 on both sides

90/21 = 30/7 = k2

So...our solution is (k1, k2)  = (11/7, 30/7 )

 

     

 Mar 18, 2015
 #1
avatar+130516 
+5
Best Answer

16= 2k1 + 3k2

25= 5k1 + 4k2      

Multiply the first equation by 4 and the second equation by -3.....this will eliminate k2.....so we have

64 =    8k1     + 12k2

-75 = -15k1    -  12k2       add these together

-11 = -7k1      divide by -7 on both sides

11/7  = k1      substitute  this into either equation to find k2  ...I'll use the first one

16 = 2(11/7) + 3k2

16= 22/7 + 3k2      subtract 22/7 from borh sides

16 - 22/7  = 3k2

[112 - 22]/7  = 3k2

90/7  = 3k2     divide by 3 on both sides

90/21 = 30/7 = k2

So...our solution is (k1, k2)  = (11/7, 30/7 )

 

     

CPhill Mar 18, 2015

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