25.5^2 +51 * 24.5+24.5^2
=25.5^2 +2*25.5 * 24.5+24.5^2
=(25.5+24.5)^2
=50^2
=2500
(102*98+4)/(252^2 -248^2)
=[(100+2)(100-2)+4]/[(252+248)(252-248)]
=(100^2-2^2+4)/(500*4)
=100^2/(100*5*4)
=100/20
=5