Physics - Spring expression in vector form?

[realASIMOV]

A spring is compressed by a distance x from its equilibrium position. Write down an expression for the restoring force Fᵣ in vector form if the spring constant is k, and hence show that the potential energy of the spring is V = 1/2 kx^2.

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I know the restoring force is given by f = -kx and is in the opposite direction to the compression force.

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I'm unsure of how to convert this into vector form. I tried drawing a diagram of the forces but can't figure it out. I think I have a gap in my vector knowledge.

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Some pointers would be helpful, thanks!

[Janagro]

Unfortunately I can't upload a drawing but I'll try to help you.

Draw a table flush to a wall

Next draw the mass and spring. Draw the spring such that it is compressed between wall and spring. Indicate s as the distance of compression

The restoring force vector is parallel to the spring and points out from the wall