Question

in this from where 200r is come

Answer 1

It is based on (a +b)^2 = a^2 + b^2 + 2ab

2×100×r

Answer 2

hello dear it is very simple

(a+b)^2=a^2+b^2+2*a*b

than according to this eq.

(100+r)^2= 10000+r^2+100*2*r

so the = 10000+r^2+200*r

hope you understand dear

ok smile :):)