Fnd a formula for a function fx y z whose level surface f

Question

Question: 1. Write the level surface x + 2y + 3z = 5 as the graph of a function f(x, y).

2. Find a formula for a function f(x, y, z) whose level surface f = 4 is a sphere of radius 2, centered at the origin.

3. Write the level surface x² + y + √z = 1 as the graph of a function f(x, y).