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|3k-2|=2|k+2|

 Aug 26, 2016
 #1
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Solve for k over the real numbers:
abs(2-3 k) = 2 abs(k+2)

 

abs(2-3 k) = 2 abs(k+2) if and only if 2-3 k = 2 (k+2) or 2-3 k = -2 (k+2):
2-3 k = 2 (k+2) or 2-3 k = -2 (k+2)

 

Expand out terms of the right hand side:
2-3 k = 2 k+4 or 2-3 k = -2 (k+2)

 

Subtract 2 k+2 from both sides:
-5 k = 2 or 2-3 k = -2 (k+2)

 

Divide both sides by -5:
k = -2/5 or 2-3 k = -2 (k+2)

 

Expand out terms of the right hand side:
k = -2/5 or 2-3 k = -4-2 k

 

Subtract 2-2 k from both sides:
k = -2/5 or -k = -6

 

Multiply both sides by -1:
Answer: |k = -2/5     or     k = 6

 Aug 26, 2016
 #2
avatar+26396 
+6

|3k-2|=2|k+2|

 

Formula:

|a|2=a2

 

|3k2|=2|k+2||square both sides(3k2)2=22(k+2)29k212k+4=4(k2+4k+4)9k212k+4=4k2+16k+165k228k12=0k1,2=28±28245(12)25k1,2=28±102410k1,2=28±3210k1=28+3210k1=6010k1=6k2=283210k2=410k2=0.4

 

laugh

 Aug 26, 2016

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