Using a2 – b2 = (a + b) (a – b), find(i) 1012 – 992(ii) (10.3

1.	Using a2 – b2 = (a + b) (a – b), find(i) 1012 – 992(ii) (10.3)2 – (9.7)2(iii) 1532 – 1472
Answer» (i) 101² – 99² = (101 + 99) (101 – 99) (Using given identity) = (200) (2) = 400 (ii) (10.3)² – (9.7)² = (10.3 + 9.7) (10.3 – 9.7) (Using given identity) = (20) (0.6) = 12 (iii) 153² – 147² = (153 + 147) (153 – 147) (Using given identity) = (300) (6) = 1800

Using a2 – b2 = (a + b) (a – b), find(i) 1012 – 992(ii) (10.3)2 – (9.7)2(iii) 1532 – 1472

Answer»

(i) 101² – 99²

= (101 + 99) (101 – 99) (Using given identity)

= (200) (2)

= 400

(ii) (10.3)² – (9.7)²

= (10.3 + 9.7) (10.3 – 9.7) (Using given identity)

= (20) (0.6)

= 12

(iii) 153² – 147²

= (153 + 147) (153 – 147) (Using given identity)

= (300) (6)

= 1800