Question

log3(x+1)+Log3(17-x)=4

Answer 1

log3(x+1)+log(17-x)=4
log3((x+1)(17-x)=log3(81)
(x+1)(17-x)=81
17x-x^2+17-x=81
-x^2+16x-64=0 |:(-1)
x^2-16x+64=0
D=b^2-4ac=(-16)^2-4*64=256-256=0
x=-b/(2a)=-(-16)/(2*1)=16/2=8
ответ: 8