Find the general expansion of (a - b)² using geometry, as we did for 55². Class 8

Find the general expansion of (a - b)² using geometry, as we did for 55². Class 8

Question 1.

Find the general expansion of (a - b)² using geometry, as we did for 55². Class 8

Solution:

So, (a — b)² = a × a - a × b - b × a + b × b

= a2 - 2ab + b²

Question 2.

Use the identity (a - b)² to find the values of (a) 99² and (b) 58². Class 8

Solution:

(a) 99² = (100 - 1)²

= 100² - 2 × 100 × 1 + 1²

= 10000 - 200 + 1 = 9801

(b) 58² = (60 - 2)² = 60² - 2 × 60 × 2 + 2²

= 3600 - 240 + 4 = 3364