Question

ncert 9th class 2.5ka 2nd question​

Answer 1

Answer:

a. Using identity, (x + a) (x + b) = x² + (a + b) x + ab :

103 × 107 = (100 + 3) (100 + 7)

= 100² + (3 + 7) (100 + 7)

= 10000 + 10 × 100 + 3 × 7

= 10000 + 1000 + 21

= 11021

Hence, 103 × 107 = 11021

b. Using identity, (x + a) (x + b) = x² + (a + b) x + ab :

95 × 96 = (100 - 5) (100 - 4)

= 100² + [(-5 - (4)] 100 + (-5) (-4)

= 10000 + (-9) 100 + 20

= 10000 - 900 + 20

= 10020 - 900

= 9120

Hence, 95 × 96 = 9120

c. Using identity, (a + b) (a - b) = a² - b² :

104 × 96 = (100 + 4) (100 - 4)

= (100)² - 4²

= 10000 - 16

= 9984

Hence, 104 × 96 = 9984

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