The value of #lim_(x -> 2) ([2 - x] + [x - 2] - x) = #? (where [.] denotes greatest integer function)

1 Answer
Jul 15, 2017

# -3.#

Explanation:

Let, #f(x)=([2-x]+[x-2]-x).#

We will find the Left Hand & Right Hand Limit of #f# as #x to2.#

As #x to 2-, x < 2;" preferably, 1 < x <2."#

Adding #-2# to the inequality, we get, #-1 lt (x-2) < 0,# and,

multiplying the inequality by #-1,# we get, #1 gt 2-x gt 0.#

# :. [x-2]=-1......., and,................. [2-x]=0.#

# rArr lim_(x to 2-) f(x)=(0+(-1)-2)=-3.......................(star_1).#

As #x to 2+, x gt 2;" preferably, "2 lt x lt 3.#

# :. 0 lt (x-2) lt 1, and, -1 lt (2-x) lt 0.#

# :. [2-x]=-1, ......., and,.............. [x-2]=0.#

# rArr lim_(x to 2+) f(x)=(-1+0-2)=-3.........................(star_2).#

From #(star_1) and (star_2),# we conclude that,

# lim_(x to 2) f(x)=lim_(x to 2) ([2-x]+[x-2]-x)=-3.#

Enjoy Maths.!