大家帮忙解决一道数学题,谢啦

f(x)=log3((mx^2+8x+n)/(x^2+1)) 值域为[0,2]
所以0<=log3((mx^2+8x+n)/(x^2+1)) <=2
1<=(mx^2+8x+n)/(x^2+1)<=9
(1-m)x*x-8x-n+1<=0
(9-m)x*x-8x+9-n>=0
方程=0有唯一解 有△=0
64-4(1-m)(1-n)=0
64-4(9-m)(9-n)=0
1-m<0 9-m>0
所以解得m=5 n=5