1.

Find the domain and the range of the real function, `f(x)=(1)/(sqrt(x+[x]))`.

Answer» We have, `f(x)=(1)/(sqrt(x+[x]))`
We know that
`{{:(x+[x]gt0"for all "xgt0),(x+[x]=0",when "x=0),(x+[x]lt0"for all "xlt0):}`
`:.f(x)=(1)/(sqrt(x+[x]))` is defined only when `x+[x]gt0` and this happens only when `xgt0`.
`:."dom "(f)=(0,oo)`.
Let y=f(x). Then,
`y=(1)/(sqrt(x+[x]))impliessqrt(x+[x])=(1)/(y)." "....(i)`
Now, `xgt0impliesx+[x]gt0impliessqrtx+[x]gt0implies(1)/(y)gt0impliesygt0`.
`:."range "(f)=(0,oo)`.
Hence, dom `(f)=(0,oo)"andrange "(f)=(0,oo)`.


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