Question

log2(x+3)+log2(x-4)=3

Answer 1

log2 (x+3) + log2 (x-4) = 3

log2 (x+3)•(x-4) = 3

(x+3).(x-4) = 2³

x²-x -12 -8 = 0

x² -x -20 = 0
∆= 1+80= 81 => √∆=9
x= 1±9/2
x' = 1+9/2 = 5 ✓ (RESPOSTA)
x" = 1-9/2 = -4 (não serve)