lg(x - 3)+ lg(x+45)=2

Question

lg(x - 3)+ lg(x+45)=2

Answer 1

((x-3)(x+45))=100

x^2+45x-3x-135=100

x^2+42x-235=0

D=42^2+4*235=V2704

 

x=-47

x=5