Answer
See below
Work Step by Step
Given: $x(t)=1+2\int^t_0 \sin (t-\tau)x (\tau) d\tau$
Taking the Laplace transformation:
$L[x(t)]=L[1+2\int^t_0 \sin (t-\tau)x (\tau) d\tau]$
we have:
$x(s)=\frac{1}{s}+2L[\sin *x(t)]$
Apply convolution theorem:
$x(s)=\frac{1}{s}+\frac{2}{s^2+1}x(s)\\
=\frac{s^2+1}{s(s^2-1)}\\
=\frac{1}{s-1}+\frac{1}{s+1}-\frac{1}{s}$
Hence, the general solution is:
$x(t)=e^{t}+e^{-t}-1$