Find the values of the following using the identity (a - b)² = a² - 2ab + b². Class 9

Find the values of the following using the identity (a - b)² = a² - 2ab + b². Class 9

Question 1.

Find the values of the following using the identity (a - b)² = a² - 2ab + b². Class 9

i. (79)²

ii. (193)²

iii. (299)²

Solution:

i. (79)² = (80 - 1)²

Here, a = 80 and b = 1

∴ (79)² = (80 - 1)²

= 80² - 2(80)(1) + 1²

= 6400 -160 + 1

= 6241

ii. (193)² = (200 - 7)²

Here, a = 200 and b = 7

∴ (193)² = (200 - 7)²

= 200² - 2(200)(7) + 7²

= 40000 - 2800 + 49 = 37249

iii. (299)² = (300 - 1)²

Here, a = 300 and b = 1

∴ (299)² = (300 - 1)² = 300² - 2(300)(1) + 1²

= 90000 - 600 + 1 = 89401