\(98^2=\left(100-2\right)^2=100^2-2\cdot2\cdot100+4=10000-400+49604\)
\(299^2=\left(300-1\right)^2=300^2-2\cdot300+1=90000-600+1=89401\)
\(63\cdot57=\left(60+3\right)\left(60-3\right)=60^2-3^2=3600-9=3591\)
\(71\cdot69=\left(70+1\right)\left(70-1\right)=70^2-1=4900-1=4899\)
mấy bạn giúp mk vớikhó quá à
\(98^2\)=98.98=9604
\(299^2\)=299.299=89401
63.57=3591
71.69=4899