(i) \(\frac{58^2-42^2}{16}\)
= \(\frac{(58-42)(58-42)}{4\times 4}\)
= \(\frac{16(100)}{16}\)
= 100
(ii) 178 x 178 - 22 x 22
(178)2 – (22)2
= (178 + 22) (178 – 22)
= 200 × 156
= 31200
(iii) \(\frac{198\times 198-102\times 102}{96}\)
= \(\frac{(198-102)(198+102)}{96}\)
= \(\frac{96\times 300}{96}\)
= 300
(iv) 1.73 x 1.73 - 0.27 x 0.27
(1.73) – (0.27)
= (1.73 + 0.27) (1.73 – 0.27)
= 2 (1.46)
= 2.92
(v) \(\frac{8.63\times 8.63-1.37\times 1.37}{0.726}\)
= \(\frac{(8.63+1.37)(8.63-1.37)}{0.726}\)
= \(\frac{10\times 7.26}{0.726}\)
= 100
