Saved Bookmarks
| 1. |
Simplify the following using the formula: (a – b) (a + b)= a2 – b2 :(i) 197 × 203(ii) 113 × 87(iii) 95 × 105 |
|
Answer» (i) 197 × 203 We can express 203 as 200 + 3 and 197 as 200 – 3 Using formula (a – b) (a + b) = a2 – b2 We get, 197 × 203 = (200 – 3) (200 + 3) = (200)2 – (3)2 = 40000 – 9 = 39991 (ii) 113 × 87 We can express 113 as 100 + 13 and 87 as 100 – 13 Using formula (a – b) (a + b) = a2 – b2 We get, 113 × 87 = (100 – 13) (100 + 13) = (100)2 – (13)2 = 10000 – 169 = 9831 (iii) 95 × 105 We can express 95 as 100 – 5 and 105 as 100 + 5 Using formula (a – b) (a + b) = a2 – b2 We get, 95 × 105 = (100 – 5) (100 + 5) = (100)2 – (5)2 = 10000 – 25 = 9975 |
|