Log2 (x-3)+log2(2x+1)=2
Log2 (x-3)+log2(2x+1)=2, x∈ [3, +∞]
log2 ((x-3) * (2x+1)) =2
log2 (2x^2 +x -6x -3)=2
2x^2 +x -6x -3=2^2
2x^2- 5x -3 =4
2x^2 -5x -3 -4 =0
2x^2 -5x-7=0
x= -(-5) ± √-(-5)^2 -4 *2*(-7) / 2*2
x= 5± √25+56/ 4
x= 5 ±√81/4
x=5±9 / 4
x= 5+9/4 x=5-9/4
x=7/2, x ∈ [3, + ∞]
x=-1
x=7/2