Question

Solve the question 

(i) 998²

(ii) (5.2)² 

(iii) 297 × 303

Answer 1

(i) 998² = (1000 − 2)²

= (1000)² − 2(1000)(2) + (2)² 

= 1000000 − 4000 + 4 = 996004

Note : [(a − b)² = a² − 2ab + b² ]

(ii) (5.2)² = (5.0 + 0.2)²

= (5.0)² + 2(5.0) (0.2) + (0.2)²

= 25 + 2 + 0.04 = 27.04

 Note : [(a + b)² = a² + 2ab + b² ]

(iii) 297 × 303 = (300 − 3) × (300 + 3) 

= (300)² − (3)² 

= 90000 − 9 = 89991

Note : [(a + b) (a − b) = a2 − b2]