89×91-59²=(90-1)×(90+1)-59²=90²-59²-1²=(90+59)×(90-59)-1=149×31-1=149×30+149×1-1=150×30-1×30+148=4500+118=4618
=5498,给个好评呗,好心有好报
4618..
89×91-59²=(90-1)x(90+1)-59²=90²-1-59²=(90+59)x(90-59)-1=149x31-1=4619-1=4618