Question

Scrieti,folosind formule de calcul prescurtat: 41 la a 2a, 49la a2a,31 ori 29 si 52 ori 48

Answer 1

Folosesti formulele (a+b)^2 = a^2 + 2ab + b^2 si (a-b)^2 = a^2 - 2ab + b^2;
De exemplu, 41^2 = (40 + 1)^2 = 40^2 + 2x40x1 + 1^2 = 1600 + 80 + 1 = 1681;
49^2 = (50-1)^2 = 50^2 -2x50x1 + 1^2 = 2500 - 100 + 1 = 2401;
Bafta!

Answer 2

41² = (40+1)² = 1600 + 2*40*1+1=1600+80+1=1681 ;

49² = (40+9)² = 1600+2*40*9+81=2401 ;

31*29 = (30+1)(30-1) = 30² - 1² = 899 ;

52*48 = (50+2)(50-2) = 50² - 2² = 2496 ;