1. Define the problem and initial conditions:
We are given the function definitions:
[a] represents the largest integer less than or equal to a,
{a}=a−[a].
We need to determine if there exist positive integers m and n and n+1 real numbers x0,x1,…,xn such that:
x0=428,xn=1928,
and
10xk+1=[10xk]+m+{5xk}.
2. **Calculate the first few values of xi:**
x0=428.
Using the given recurrence relation:
10x1=[10428]+m+{5428}.
Calculate each term:
[10428]=42,
{5428}=5428−[5428]=85.6−85=0.6.
Therefore:
10x1=42+m+0.6=42.6+m,
x1=10(42.6+m)=426+10m.
3. **Calculate x2:**
10x2=[10x1]+m+{5x1}.
Since x1=426+10m:
[10426+10m]=42+m,
{5426+10m}=5426+10m−[5426+10m]=85.2+2m−(85+2m)=0.2.
Therefore:
10x2=42+m+m+0.2=42+2m+0.2,
x2=10(42+2m+0.2)=422+20m.
4. **Calculate x3:**
10x3=[10x2]+m+{5x2}.
Since x2=422+20m:
[10422+20m]=42+2m,
{5422+20m}=5422+20m−[5422+20m]=84.4+4m−(84+4m)=0.4.
Therefore:
10x3=42+2m+m+0.4=42+3m+0.4,
x3=10(42+3m+0.4)=424+30m.
5. **Calculate x4:**
10x4=[10x3]+m+{5x3}.
Since x3=424+30m:
[10424+30m]=42+3m,
{5424+30m}=5424+30m−[5424+30m]=84.8+6m−(84+6m)=0.8.
Therefore:
10x4=42+3m+m+0.8=42+4m+0.8,
x4=10(42+4m+0.8)=428+40m.
6. Analyze the periodic behavior:
Notice that:
x1≡6(mod10),
x2≡2(mod10),
x3≡4(mod10),
x4≡8(mod10).
This pattern repeats every 4 steps. Therefore, for xn=1928, we must have:
x4k=1928.
Given:
x4k=428+40mk=1928,
40mk=1500.
Since 1500 is not divisible by 40, there are no positive integers m and k that satisfy this equation.
The final answer is False.