Question

Evaluate the following using properties of the perfect Square
(278)²-(277)²​

Answer 1

★ Answer :

★ Method : 1

We know that,

a² - b² = (a + b)(a - b)

→ 121² - 120²

→ (121 - 120)(121 + 120)

→ (1)(241)

→ 241

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★ Method 2 :

We csn write 121 as (100 + 21) and 120 as (100 + 20)

We know that,

(a + b)² = a² + b² + 2ab

→ (100 + 21)² - (100 + 20)²

→ (100)² + (21)² + 2(100)(21) - [(100)² + (20)² + 2(100)(20)]

→ (100)² + (21)² + 2(100)(21) - (100)² - (20)² - 2(100)(20)

→ 441 + 4200 - 400 - 4000

→ 4641 - 4400

→ 241

Answer 2

Answer:

555

Step-by-step explanation:

a² - b² = (a + b)(a - b)

a = 278; b = 277

( 278 + 277 ) X ( 278 - 277 )

( 555 ) X ( 1 )

555