LTSpice: how to setup sinusoidal or exponential voltage source?
Why not using an Arbitrary Behavioral Voltage?
In LTspice, you can enter the equations directly by adjusting the V=F(...) to V=10*sin(24*time) + 14 and for the other source with V= 12 + 15*exp(-200*time).

(Note you should use "time", not "t" )