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let-f-x-1-x-1-x-1-prove-that-f-is-periodic-with-period-1-2-give-a-expression-of-f-x-when-x-0-1-




Question Number 40090 by maxmathsup by imad last updated on 15/Jul/18
let f(x)= 1−[x]−[1−x]  1) prove that f is periodic with period 1  2) give a expression of f(x) when  x∈[0,1[
letf(x)=1[x][1x]1)provethatfisperiodicwithperiod12)giveaexpressionoff(x)whenx[0,1[
Commented by math khazana by abdo last updated on 29/Jul/18
1) first we have f(x)=1−[x]−1−[−x]  =−[x]−[−x] ⇒  f(x+1) =−[x+1]−[−(x+1)]  =−[x]−1−[−x]+1=f(x) so f is periodic with  T=1  2) if 0≤x<1 [x]=0 and −1<−x≤0 ⇒[−x]=−1 ⇒  f(x)=−[−x]=−(−1)=1 .
1)firstwehavef(x)=1[x]1[x]=[x][x]f(x+1)=[x+1][(x+1)]=[x]1[x]+1=f(x)sofisperiodicwithT=12)if0x<1[x]=0and1<x0[x]=1f(x)=[x]=(1)=1.

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