Question

ALGEBRAIC EXPRESSIONS AND IDENTITIES:
HOW TO SOLVE (9.9)^2 and (8.9)^
URGENT.PLZ ANSWER FAST

Answer 1

Answer:

1 ) 9.9² = 98.01

2 ) 8.9² = 79.21

Step-by-step explanation:

1 ) ( 9.9 )² = ?

9.9 can be written as ( 10 - 0.1 )

⇒ 9.9² = ( 10 - 0.1 )²

This is of the form ( a - b )² which is equal to ( a² - 2ab + b² )

⇒ ( 10 - 0.1 )² = ( 10² - 2 × 10 × 0.1 + 0.1² )

⇒ ( 10 - 0.1 )² = ( 100 - 2 + 0.01  )

⇒ ( 10 - 0.1 )² = 98.01

⇒ 9.9² = 98.01

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2 ) 8.9² can be written as ( 10 - 1.1 )²

⇒ ( 10 - 1.1 )² = ( 10² - 2 × 10 × 1.1 + 1.1² )

⇒ ( 10 - 1.1 )² = ( 100 - 22 + 1.21 )

⇒ ( 10 - 1.1 )² = ( 79.21 )

⇒ 8.9² = 79.21

Hence these are the required answers

Algebraic Identities used : ( a - b )² = ( a² - 2ab + b² )

Answer 2

hey.

since (a-b) ² = a² + b² - 2ab

to find (9.9)² :

= (10 - 0.1)²

= (10)² + (0.1)² - 2(10)(0.1)

= 100 + 0.01 - 2

= 98.01

To find (8.9)² :

= (10-1.1)²

= (10)² + (1.1)² - 2(10)(1.1)

= 100 + 1.21 - 22

= 79.21

hope it helps you!