(i)(5+√7)(2+√5)=10+5√5+2√7+√35=32.3888(ii)(5+√5)(5−√5)=52−(√5)2[Using,(a−b)(a+b)=a2−b2]=25−5=20(iii)(√3+√7)=4.377(iv)(√11−√7)(√11+√7)=11−7=4