①800²-1600×798+798²
=800²-2x800×798+798²
=(800-798) ²
=2²
=4
② 99²+198+1分之100
99²+198+1
= 99²+2x99x1+1²
=(99+1)²
=100²
99²+198+1分之100=100分之1
①800²-1600×798+798²
=800²-2x800×798+798²
=(800-798) ²
=2²
=4
② 99²+198+1分之100
99²+198+1
= 99²+2x99x1+1²
=(99+1)²
=100²
99²+198+1分之100=100分之1