Question

Using identities, express 9.8 x 10.2

Answer 1

9.8=10-0.2
10.2=10+0.2
a=10
b=0.2
(10-0.2) (10+0.2)=(a-b) (a+b)
(a-b) (a+b) = a²-b²
                   = 10²- 0.2²
                   =100-0.04
                   = 99.96