Square of Binomial: $(a+b)_{2}=a_{2}+2ab+b_{2}$ $(a−b)_{2}=a_{2}−2ab+b_{2}$ Difference of Square: $a_{2}−b_{2}=(a+b)(a−b)$

Find the value of $25−36$ We have $25−36$ $=5_{2}−6_{2}$ Apply Identity $a_{2}−b_{2}=(a+b)(a−b)$ $=(5+6)(5−6)$ $=−11$