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show that 2/√(12)-√(8) can be written in the form √a +√b

 Oct 9, 2016
 #1
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show that 2/√(12)-√(8) can be written in the form √a +√b

 

 Oct 9, 2016
 #2
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Simplify the following:
2/sqrt(12)-sqrt(8)

sqrt(12) = sqrt(2^2×3) = 2 sqrt(3):
2/2 sqrt(3)-sqrt(8)

2/(2 sqrt(3)) = 2/2×1/sqrt(3) = 1/sqrt(3):
1/sqrt(3)-sqrt(8)

sqrt(8) = sqrt(2^3) = 2 sqrt(2):
1/sqrt(3)-2 sqrt(2)

Rationalize the denominator. 1/sqrt(3) = 1/sqrt(3)×(sqrt(3))/(sqrt(3)) = (sqrt(3))/(3):
(sqrt(3))/(3)-2 sqrt(2)

Put each term in (sqrt(3))/(3)-2 sqrt(2) over the common denominator 3: (sqrt(3))/(3)-2 sqrt(2) = (sqrt(3))/(3)+(-6 sqrt(2))/(3):
(sqrt(3))/(3)+(-6 sqrt(2))/(3)

(sqrt(3))/(3)-(6 sqrt(2))/(3) = (sqrt(3)-6 sqrt(2))/(3):
Answer: | (sqrt(3)-6 sqrt(2))/(3)=1/sqrt(3)-2 sqrt(2)=- 2 sqrt(2) + 1/sqrt(3)

 Oct 9, 2016

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