1)f:n->{24,27,30,...}
such that f(x)=3x+21
determine the function f?
a)f is 1-1
b)f is onto
c)f is into
d)f is bijective

2)A circle circumscribes three unit circles that touch each other.what is the area of the larger circle?
a015.6
b)14.9
c)12.4
d)17.3

3)one guy went to fruit stall to buy oranges.he found that price of one orange is reduced by 3rs and so he bought 30 instead of 20.howmuch money he had?
a)160
b)150
c)180
d)170

• (3):30*(x-3)=20*x ,x=9 ,Total Money=20*x=180 ans.
• 11 years agoHelpfull: Yes(27) No(1)
• domain: {1,2,3,4...}
  Range=co-domain= : {24,27,30,33....}
  a bijective function is that, which is both one-one and onto.
  1-1 correspondence is there, as each element in domain is linked with a single element in range. now onto functions are that, in which all the elements of co-domain has a linkage in domain.
  hence its both 1-1 and onto, hence bijective
• 11 years agoHelpfull: Yes(15) No(0)
• sol for 2nd:
  3 unit circle => each of radius=1
  constructing the figure accordingly,we get to find out the radius of larger circle(r) i.e., the circle circumscribing them
  if u are familiar with geometry concepts u will get cos30=1/(r-1)
  solving this we will get r=2.167 and hence area approx 14.9
  
  there is no chance to construct figure here, so cant clarify further if u didnt get me...
• 11 years agoHelpfull: Yes(10) No(0)
• answer for 3rd que. 180
  let price of one orange is x
  if price of orange not reduced, he could buy 20.
  if the price reduced by rs 3 then he could by 30.
  therefore 20x=30(x-3)
  by solving this x is 9
  therefore he has 180 rs.
• 11 years agoHelpfull: Yes(8) No(0)
• 1)ans:a)f is 1-1
• 11 years agoHelpfull: Yes(4) No(1)
• (2)Ans-b-14.9
• 11 years agoHelpfull: Yes(3) No(0)
• answer for 3rd que. 180
  let price of one orange is x
  if price of orange not reduced, he could buy 20.
  if the price reduced by rs 3 then he could by 30.
  therefore 20x=30(x-3)
  by solving this x is 9
  therefore he has 180 rs.
• 11 years agoHelpfull: Yes(2) No(0)
• sami wardhan karn please justify 2nd question's answer
  
• 11 years agoHelpfull: Yes(1) No(0)
• total amount of money is 180
• 11 years agoHelpfull: Yes(1) No(1)
• (1)bijective function or one-to-one correspondence) is a function giving an exact pairing of the elements of two sets.
  so the answer is "D"
• 11 years agoHelpfull: Yes(0) No(0)
• @dhruv how saying bijective pls explain
• 11 years agoHelpfull: Yes(0) No(0)
• SOMEONE PLS GVE CLEAR EXPLANATION TO 1ST QUESTION
• 11 years agoHelpfull: Yes(0) No(0)
• 1. It is one-one and also onto as "A function f from A to B is called onto if for all b in B there is an a in A such that f (a) = b. All elements in B are used."
  So it is bijective. Ans. (d)
  2. 30(x-3)=20x => x=9 => 20*9=180 Ans. (c)
• 11 years agoHelpfull: Yes(0) No(0)
• @neelam: how did u get cos30 = 1/(r-1) ???
• 11 years agoHelpfull: Yes(0) No(0)