lim(x->0) [f(1-2x）- f（1+3x）]/x
=lim(x->0) { [f(1-2x)-f(0)] - [ f(1+3x)-f(0)] } /x
=lim(x->0) [f(1-2x)-f(0)]/x - lim(x->0) [ f(1+3x)-f(0)] /x
=(-2)*lim(x->0) [f(1-2x)-f(0)]/(-2x) - 3*lim(x->0) [ f(1+3x)-f(0)] /(3x)
=(-2)*f'(0) - 3*f'(0)
= -4 - 6
= -10