given equation is
x+3x−1>0 as x-1 is in denominator it must not be equal to zero
therefore x not equals to 1
let x be >1
then the equation becomes
x+3>0(x−1)
⇒x>−3 and we assumed x>1 therefore the solution for this case is x∈(1,∞)
now let x<1,
then the equation becomes
x+3<0(x−1)
⇒x<−3 and we assumed that x<1 therefore the solution for this case is x∈(−∞,−3)
therefore the overall solution is x∈(−∞,−3)∪(1,∞)