3^{2x+3}-4^{3x+1}+1=0

3^{2x+3}+1 = 4^{3x+1}

The only powers of 3 and 4 that I can see, which differ by 1 is 3^1+1=4^1
That requires 2x+3=1 and 3x+1=1, which has no solution.
So, a graphical or iterative approach needs to be used.
I get x=0.9756
that's near x=1, where 3^5+1=244 and 4^4=256. Sounds reasonable.