Question

The value of (107)${}^2$ - (93)${}^2$ is:

• A. 20018
• B. 10018
• C. 23482
• D. 36482

Answer 1

The correct option is A 20018

(107)${}^2$ can be written as (100+7)${}^2$,
(93)${}^2$ can be written as (100-7)${}^2$.
Using the identity (a+b)${}^2$ - (a-b)${}^2$ = 2(a${}^2$+b${}^2$),
(107)${}^2$ - (93)${}^2$ = 2(100${}^2$+3${}^2$) = 20018.