Question

use identities to evaluate 105 into 98 ​

Answer 1

Solution:

105 * 98

= ( 100 + 5 ) * ( 100 - 98 )

Using Identity: (x+a) (x-b) = x2 + (a-b)x - ab

where x= 100, a= 5, b = 2

= (100)2 + (5-2)100 - 5(2)

= 10000 + 3(100) - 10

= 10000 + 300 - 10

= 10000 + 290

= 10290