Question

solve by using suitable identity 103×105

Answer 1

$= (100 + 3) \times (100 + 5) \\ = 10000 + 500 + 300 + 15 \\ = 10815$
identity
(x+a)(x+b)=x²+xb+ax+ab
=x²+(a+b)x+ab

Answer 2

103×105
(100+3) (100+5)
Identity
(x+a) (x+b)=x^2+(a+b)x+a×b
= 100^2+(3+5)100+3×5
=10000+8×100+15
=10000+800+15
=10815.