If the x within the natural logarithm is always positive, for example x = 3x² + 5, should ∫x over 3x²+5 dx be expressed as intx over 3x²+5 dx =1 over6 ln (3x²+5) + c or intx over 3x²+5 dx =1 over6 ln |3x²+5| + c? Would it be wrong to use absolute value brackets instead of brackets if the value inside is always positive? Is it necessary to take into account the possibility of x being a complex number / an imaginary number and thus making ln (3x²+5) negative? Which expression is more accurate?