Question

using identity find (21² - 19²).
please answer it fast please​

Answer 1

Answer:

Hope it helps you dear :)

Answer 2

$\sf{\underline{\overline{\red{Given :}}}}$

using identity find (21² - 19²).

$\sf{\underline{\overline{\pink{Solution :}}}}$

⇛ 21 can be written as (20 + 1)

⇛ 19 can be written as (20 – 1)

⇛ (20 + 1) × (20 – 1)

Using the identity :

⇛ ( a + b) × ( a – b) = a² – b²

⇛ (20)² – (1)² = 400 – 1

$\fbox\purple{⇛399}$