Объяснение:
51² = ( 50 +1 )² = 50² + 2*50*1 + 1 = 2500 +100+1 =2601
39² = (40 - 1)² = 40² -2*40*1 + 1 = 1600 - 80 +1 = 1521
103² = ( 100 +3)² = 100² + 2*100*3 +3² = 10000+600 +9 =10609
999² = ( 1000 - 1) = 1000² -2*1000*1 +1 = 1 000 000 - 2000 +1 = 998 001
1001² = ( 1000 +1)² = 1 000 000 +2*1000*1 +1 = 1 002 001
51² -41² =(51-41)(51+41) = 10*92 = 920
76² -24² =( 76 -24)(76+24) = 52 * 100 = 5200
697² -303² +( 697 -303)( 697 +303) = 394*1000 =394000
101 * 99 = ( 100+1)(100-1) = 100² -1² = 10000 -1 =9999
(92² - 48²) / (27²- 17²) = (92 -48)(92+48) / (27 -17)(27+17) =
= 44* 140/10*44 = 14
(53² -25²)/(79² -51²) = (53-25)(53+25)/(79-51)(79+51) = 28*78/28*130 = 78/130 = 39/65 =3/5
(63² -27²) / (83² -79²) = ( 63-27)( 63+27) / ( 83-79)( 83+79) = 36*90 / 4 *162 = 9*30/54 =30/6 =5
