Question

Вычислите: (тема "Формулы Сокращенного Умножения") 1)(30+1)(30-1); 2)61•59; 3)199•201; 4)72•68; 5) 55²-45²; 6)41²-31²; 7)76²-24²; 8)37²-23².

Answer 1

1 ) ( 30+1 ) ( 30-1 ) = 30² - 1² = 900 - 1 = 899
2 ) 61 * 59 = ( 60 + 1 ) ( 60 - 1 ) = 3600-1 = 3599
3 ) 199 * 201 = ( 200 + 1 ) ( 200 - 1 ) = 40000 - 1 = 39999
4 ) 72 * 68 = ( 70 + 2 ) ( 70 - 2 ) = 4900 - 4 = 4896
5 ) 55² - 45²= ( 55 - 45 ) ( 55 + 45 ) = 3025 - 2025 = 1000
6 ) 41² - 31² = ( 41 - 31 ) ( 41 + 31 ) = 1681 - 961 = 720
7 ) 76² - 24² = ( 76 - 24 ) (76 + 24 ) = 5776 - 576 = 5200
8 ) 37² - 23² = ( 37 - 23 ) ( 37 + 23 ) = 1369 - 529 = 840 

Answer 2

1)30^2–1^2=900–1=899;
2)61*59=(60+1)(60–1)=3600–1=3599;
3)(200–1)(200+1)=40000–1=39999; 4)(70+2)(70–2)=4900–4=4896; 5)(55–45)(55+45)=10*100=10000;6)(41–31)(41+31)=10*72=720;7)(76–24) (76+24)=52*100=5200;8)(37–23)(37+23)=14*60=840