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Grade 11Algebra

Please answer the question as soon as possible thanks

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Profile image of Chandan Kumar
8 Years agoGrade 11
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1 Answer

Profile image of Samyak Jain
ApprovedApproved Tutor Answer8 Years ago
f(x) = ( 2 + x – [x] ) / (1 – x + [x] )
We know that x = [x] + {x}, where [x] and {x} denote greatest integer of x and fractional part off x respectively.
So, f(x) = ( 2 + [x] + {x} – [x] ) / ( 1 – [x] – {x} + [x] )
             = ( 2 + {x} ) / ( 1 – {x} )
Let y be any general value of f(x) corresponding to some x.
\therefore y = ( 2 + {x} ) / ( 1 – {x} )
y – y {x} = 2 + {x}  ;  (y + 1) . {x} = y – 2 
So {x} = (y – 2) / (y + 1)
Also, we know that 0 \leq {x} < 1 . So, 
Hence, 0 \leq (y – 2) / (y + 1) < 1 , which implies
     y – 2 \geq 0  i.e.  y \geq 2                    …......................(1)
or  y – 2 < y + 1 i.e. – 2 < 1, which is true for all y \in R   …............... (2)
Taking intersection of (1) & (2), we get 
\in [ 2 , infinity)
\therefore Range of f(x) is [ 2 , infinity)