I think you should solve this question by yourself. I'm giving you some simple tricks to find out whether the given equation perform SHM or not. Follow this :

Any equation performing a simple harmonic motion has two properties that can be used to determine the nature. 

1. Relation between acceleration and displacement of the object assumed to be undergoing an SHM.
2. SHM usually involves conservation of energy.

An object is undergoing simple harmonic motion (SHM) if;

• the acceleration of the object is directly proportional to  its displacement from its equilibrium position.
• the acceleration is always directed towards the equilibrium position.

The simple harmonic differential equation is

d²x/dt²=−ω²x

a=-w²x

Where x is the displacement from initial position, its double differentiation is acceleration and ω is the angular frequency.

If the equation obeys this differential equation then you have a simple harmonic function.

Simplest way to recognize whether a function is SHM or not, check whether the function consists of a sine or a cosine term or not.

If it consists any sine or cosine term it will surely be simple harmonic.