Question

using suitable identities (10.2)²-(9.8)²​

Answer 1

Answer:

${x}^{2} - {y}^{2} = (x + y)(x - y) \\ {(10.2)}^{2} - {(9.8)}^{2} = \\ (10.2 + 9.8)(10.2 - 9.8) \\ = 20 \times 0.4 \\ = 8$

Answer 2

Answer:

Step-by-step explanation:

Q. using suitable identities (10.2)²-(9.8)²​

Ans -  (10+0.2)²-(10-0.2)²​

now this shows (a)²-(b)²​ = (a+b)(a-b)

(10+0.2)²-(10-0.2)²​

= (10+0.2+10-0.2)(10+0.2-10+0.2)

= (20)(0.4)

=8