a=1/(√3+√2) b=1/(√3-√2) a�0�5-4ab+b�0�5=a�0�5-2ab+b�0�5-2ab=(a-b)�0�5-2ab =【1/(√3+√2)-1/(√3-√2)】�0�5-2x1/(√3+√2)x1/(√3-√2) ={【(√3-√2)-(√3+√2)】/(√3+√2)x(√3-√2)}�0�5-2/(3-2) ={-2√2/(3-2)}�0�5-2 =8-2=6