The equation should be
μ ( t ) = exp ( ∫ ∂ g ∂ x − ∂ f ∂ t f ( t ) ) d t {\displaystyle \mu (t)=\exp \left(\int {\frac {{\frac {\partial g}{\partial x}}-{\frac {\partial f}{\partial t}}}{f}}(t)\right)dt} .
