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If x + 1/x = √40 and x > 1, what is the value of x - 1/x ?
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03 Mar 2022, 04:00
03 Mar 2022, 04:00
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Expert Reply
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Question Stats:
63% (01:40) correct
36% (02:04) wrong based on 11 sessions
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If \(x+\frac{1}{x}=√40\) and \(x>1\), what is the value of \(x-\frac{1}{x}\)?
A. 4
B. 5
C. 6
D. 24
E. 36
A. 4
B. 5
C. 6
D. 24
E. 36
Re: If x + 1/x = 40 and x > 1, what is the value of x - 1/x ?
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08 Mar 2022, 20:25
08 Mar 2022, 20:25
1
\(x+\frac{1}{x}=√40\) and \(x>1\)
\((x + \frac{1}{x})^2 = 40\)
\(x^2 + \frac{1}{x^2} = 40 - 2 = 38\)
\((x - \frac{1}{x})^2 = x^2 + \frac{1}{x^2} - 2\)
\((x - \frac{1}{x})^2 = 36\)
\(x - \frac{1}{x} = 6\)
Answer C
\((x + \frac{1}{x})^2 = 40\)
\(x^2 + \frac{1}{x^2} = 40 - 2 = 38\)
\((x - \frac{1}{x})^2 = x^2 + \frac{1}{x^2} - 2\)
\((x - \frac{1}{x})^2 = 36\)
\(x - \frac{1}{x} = 6\)
Answer C
Re: If x + 1/x = 40 and x > 1, what is the value of x - 1/x ?
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08 Mar 2022, 23:25
08 Mar 2022, 23:25
1
Root 40 = 2 root 10 ,
(root 9 = 3)
2*3=6 , so you can tell it is just a bit bigger than 6
So C (as c is 6 + 1/6).
(root 9 = 3)
2*3=6 , so you can tell it is just a bit bigger than 6
So C (as c is 6 + 1/6).
