First, set x=0 to test the proposition:
2(0+1)-3(0+1)=2-3=-1, so the proposed identity is false.
This disproves the identity, but is an equation which is only true for specific values of x.
When solved as an equation, x=42.54°, 80.62°, 118.23°, 158.35°, 222.54°, 260.62°, 298.23°, 338.35° approximately for values between 0° and 360°.