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# Where do I start, and how?

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How do I begin this problem?

Guest Aug 25, 2017

#1
+26102
+2

Start by setting: $$u=\sqrt{11-x^2}\\ .\\u-\frac{2}{u}=1\\$$

Rearrange:  $$u^2-u-2=0\\.\\(u-2)(u+1)=0$$

So u = 2 or u = -1.  However, the original square root must be positive, so only the first value of u is valid.

$$\sqrt{11-x^2}=2\\.\\11-x^2 = 4\\.\\x^2=7\\.\\x=\pm \sqrt7$$

Alan  Aug 25, 2017
Sort:

#1
+26102
+2

Start by setting: $$u=\sqrt{11-x^2}\\ .\\u-\frac{2}{u}=1\\$$

Rearrange:  $$u^2-u-2=0\\.\\(u-2)(u+1)=0$$

So u = 2 or u = -1.  However, the original square root must be positive, so only the first value of u is valid.

$$\sqrt{11-x^2}=2\\.\\11-x^2 = 4\\.\\x^2=7\\.\\x=\pm \sqrt7$$

Alan  Aug 25, 2017
#2
+7
0

¿Cómo escribes para publicar tu pregunta?

RUTH1998  Aug 25, 2017

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