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how do I solve 2/(sqrt(4sqrt(2)+6))+2/(sqrt(6-4*sqrt(2)) , without calculator, it's been an hour at least..

 Apr 21, 2016
 #1
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Simplify the following:
2/sqrt(4 sqrt(2)+6)+2/sqrt(6-4 sqrt(2))

 

Factor 2 out of 6+4 sqrt(2) giving 2 (3+2 sqrt(2)):
2/( sqrt(2 (3+2 sqrt(2)) ) )+2/sqrt(6-4 sqrt(2))

 

Factor 2 out of 6-4 sqrt(2) giving 2 (3-2 sqrt(2)):
2/sqrt(2 (3+2 sqrt(2)))+2/( sqrt(2 (3-2 sqrt(2)) ) )

 

2 (3+2 sqrt(2))  =  4+4 sqrt(2)+2  =  4+4 sqrt(2)+(sqrt(2))^2  =  (2+sqrt(2))^2:
2/( sqrt((2+sqrt(2))^2 ) )+2/sqrt(2 (3-2 sqrt(2)))

 

Cancel exponents. sqrt((2+sqrt(2))^2) = 2+sqrt(2):
2/2+sqrt(2)+2/sqrt(2 (3-2 sqrt(2)))

 

2 (3-2 sqrt(2))  =  4-4 sqrt(2)+2  =  4-4 sqrt(2)+(sqrt(2))^2  =  (2-sqrt(2))^2:
2/(2+sqrt(2))+2/( sqrt((2-sqrt(2))^2 ) )

 

Cancel exponents. sqrt((2-sqrt(2))^2) = 2-sqrt(2):
2/(2+sqrt(2))+2/2-sqrt(2)

 

Multiply numerator and denominator of 2/(2+sqrt(2)) by 2-sqrt(2):
(2 (2-sqrt(2)))/((2+sqrt(2)) (2-sqrt(2)))+2/(2-sqrt(2))

 

(2+sqrt(2)) (2-sqrt(2)) = 2×2+2 (-sqrt(2))+sqrt(2)×2+sqrt(2) (-sqrt(2)) = 4-2 sqrt(2)+2 sqrt(2)-2 = 2:
(2 (2-sqrt(2)))/(2)+2/(2-sqrt(2))

 

(2 (2-sqrt(2)))/(2) = 2/2×(2-sqrt(2)) = 2-sqrt(2):
2-sqrt(2)+2/(2-sqrt(2))

 

Multiply numerator and denominator of 2/(2-sqrt(2)) by 2+sqrt(2):
2-sqrt(2)+(2 (2+sqrt(2)))/((2-sqrt(2)) (2+sqrt(2)))

 

(2-sqrt(2)) (2+sqrt(2)) = 2×2+2 sqrt(2)-sqrt(2)×2-sqrt(2) sqrt(2) = 4+2 sqrt(2)-2 sqrt(2)-2 = 2:
2-sqrt(2)+(2 (2+sqrt(2)))/(2)

 

(2 (2+sqrt(2)))/(2) = 2/2×(2+sqrt(2)) = 2+sqrt(2):
2-sqrt(2)+2+sqrt(2)

 

2-sqrt(2)+2+sqrt(2) = 4:
Answer: |  4

 Apr 21, 2016
 #2
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how do I solve 2/(sqrt(4sqrt(2)+6))+2/(sqrt(6-4*sqrt(2)) , without calculator, it's been an hour at least..

 

26+42+2642=2(16+42+1642)=2(642+6+426+42642)=2(642+6+42(6+42)(642))=2(642+6+4236162)=2(642+6+424)=2(642+6+422)=642+6+42

26+42+2642=642+6+42|()2=(642+6+42)2=(642)+26426+42+(6+42)=6+26426+42+6=12+26426+42=12+2(642)(6+42)=12+236162=12+24=12+22=12+4=1626+42+2642=4

 

laugh

 Apr 21, 2016

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