1. 45²-15²= 45×45-15×15= 2025-225=1800
2. 33²-17²= 33×33-17×17= 1089-289=800
3.(5⅔)²-(3½)²= 17/3× 17/3 - 10/3 ×10/3 = 289/9 - 100/9= 189/9 = 21
1. 45²-15²= 45×45-15×15= 2025-225=1800
2. 33²-17²= 33×33-17×17= 1089-289=800
3.(5⅔)²-(3½)²= 17/3× 17/3 - 10/3 ×10/3 = 289/9 - 100/9= 189/9 = 21