Assumptions:

We will take the new equilibrium position as y= 0

and points above it are -ve and below it are positive

Steps:

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We will use

SHM's equation

given by

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1) use equation

kx= mg

to get value of k, x here is 2inch

2)

Here since the block is initially above the new equilibrium position so we will

have phase constant

and

3) Angular frequency is given by

4) A here stands for amplitude its = 3inch in your question

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That's how I do it.

Incase if you use any other position as Y = 0 than add a constant "c" in SHM's equation

Where

c will be given by the displacement of this new position from the equilibrium position.