11. If (√5) = 2.236 and (√(10)) = 3.162 then the value of ((15)/( (√(10))+(√(20))+(√(40))−(√5)−(√(80)))) is (a) 5.398 (b) 4.398 (c) 3.398 (d) 6.398 12. If x=(((√3)+1)/3) then x^3 +(1/(x^3 ))=? (a) ((28(√3) +15)/8) (b) ((28(√3)−15)/8) (c) ((27(√3)−35)/4) (d) ((27(√3)+35)/4) 13. Simplify ((x^4 ((x^3_ ((x^2 (√x)))^(1/3) ))^(1/4) ))^(1/5) (a) x^((23)/(24)) (b) x^((23)/6) (c) x^(5/6) (d) x^((119)/(120)) 14. ((3+2(√5))/(4−2(√5)))=p+q(√5) where p and q are rational numbers then values of p and q respectively are (a) −8 −(7/2) (b) 8 −(7/2) (c) 4 7 (d) −4 −7 16. 2.6^− − 0.8^− 2^− is equal to (a) ((181)/(999)) (b) ((82)/(99)) (c) ((182)/(99)) (d_(If) ) Non of these 17. If x=3(√5)+2(√2) and y=3(√5)−2(√2) then the value of (x^2 −y^2 )^2 is (a) 5760