选C
8.6^2=73.96
x^2=0.7396
x=土0.86^是社么意思？再详细些行吗？^是次方的意思，我想楼主题目打错了吧原题目应该是8.6的平方，也就是8.6^2x^2＝0.7396=73.96×0.01x=√（73.96×0.01）=8.6×0.1=0.86√是根号的意思