The Total solution for NCERT class 6-12
Using a2 – b2 = (a + b) (a – b), find(i) 512 – 492(ii) (1.02)2 – (0.98)2(iii) 1532 – 1472(iv) 12.12 – 7.92
(i)512 – 492 = (51 + 49) (51 – 49) = 100 × 2 = 200(ii) (1.02)2 – (0.98)2 = (1.02 + 0.98) (1.02 – 0.98) = 2.00 × 0.04 = 0.08(iii) 1532 – 1472 = (153 + 147) (153 – 147) = 300 × 6 = 1800(iv) 12.12 – 7.92 = (12.1 + 7.9) (12.1 – 7.9) = 20.0 × 4.2 = 84