Using the formula (a - b)2 = (a2 - 2ab + b2), evaluate:
(i) (196)2 (ii) (689)2 (iii) (891)2
(i) We know that,
(a – b)2 = (a2 – 2ab + b2)
We have
(196)2 = (200 - 4)2
= 2002 – 2 (200 × 4) + 42
= 40000 – 1600 + 16
= 3814
(ii) We know that,
(a – b)2 = (a2 – 2ab + b2)
We have
(689)2 = (700 - 11)2
= 7002 – 2 (700 × 11) + 112
= 490000 – 15400 + 121
= 474721
(iii) We know that,
(a – b)2 = (a2 – 2ab + b2)
We have
(891)2 = (900 - 9)2
= 9002 – 2 (900 × 9) + 92
= 810000 – 16200 + 81
= 793881