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Find the domain of the following functions. If possible, give a description of the domains (for example, all points outside a sphere of radius 1 centered at the origin). $$f(w, x, y, z)=\sqrt{1-w^{2}-x^{2}-y^{2}-z^{2}}$$

Short Answer

Expert verified
Answer: The domain of the function is all points (w, x, y, z) in 4-dimensional space such that \(w^2 + x^2 + y^2 + z^2 \leq 1\), which represents the points inside or on the surface of a sphere of radius 1 centered at the origin (0,0,0,0). The domain can be written as: $$\{(w,x,y,z) \in \mathbb{R}^4 : w^2 + x^2 + y^2 + z^2 \leq 1\}$$

Step by step solution

01

Write down the inequality for the real output

Since the output of a square root should be real, we need to have the expression under the square root to be greater than or equal to zero, as follows: $$1 - w^2 - x^2 - y^2 - z^2 \geq 0$$
02

Rearrange the inequality so that all terms are on the left side

We want to rearrange the inequality by moving all terms to the left side: $$w^2 + x^2 + y^2 + z^2 \leq 1$$
03

Interpret the inequality geometrically

Observe that the left-hand side of the inequality is the sum of the squares of the coordinates in 4-dimensional space. Therefore, geometrically, the inequality represents the equation of a sphere in 4D space, with radius 1 and centered at the origin (0,0,0,0).
04

Describe the domain

From the previous step, we see that the inequality \(w^2 + x^2 + y^2 + z^2 \leq 1\) represents a sphere in 4D space. Therefore, the domain of the function is all points inside or on the surface of this sphere, including the origin. This can be written as: $$\{(w, x, y, z) \in \mathbb{R}^4 : w^2 + x^2 + y^2 + z^2 \leq 1\}$$

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