Q. How did you do that 7 8 x + 4 5 y 2 Share with your friends Share 0 Sandeep Saurav answered this Dear Student, (78x+45y)2Using (a+b)2=a2+b2+2ab=(78x)2+(45y)2+2×78x×45y=4964x2+1625y2+78x×85y (multiplied 2 with 4 and cancel with 8 )=4964x2+1625y2+75xy Regards 1 View Full Answer Saumya Pandey answered this Dekho 8 2 se cancel hua toh 4 aaya aur phir 4 4 se cancel hua toh sab cancel ho gaya aur last me bacha 7 %5xy 0