Opposing spring oscillation with mass

[smhippe]

Homework Statement

A 36 kg mass is placed on a horizontal frictionless surface and then connected to
walls by two springs with spring constants k1 = 3 N/m and k2 = 4 N/m. What is the
frequency, f (in Hz), of oscillation for the 36 kg mass if it is displaced slightly to one
side?

Homework Equations

The Attempt at a Solution

So, I wasn't sure if the spring constant added linearly or if something crazy happened. If it did then I was thinking it would be possible to plug in some numbers into the energy equations. From there plug it into the SHM equations. I'm not sure if that works at all though. Thanks!

 

[rock.freak667]

Start by drawing a free body diagram.

The springs are on opposite sides of the mass, so you can't just add them.

In equilibrium, the initial extension is zero. So if you displace it x to one side, how will the forces act?