# include & ltstdio.h & gt
# include & ltmath.h & gt
void main()
{
浮點x,b;
printf("請輸入壹個數字!");
printf(" \ n ");
scanf("%f ",& ampx);
if(x & lt;5)
b = fabs(x);
else if(5 & lt;= x & amp& ampx & lt20)
b = 3 * x * x-2 * x+1;
else if(x & gt;=20)
b = x/5;
printf("%f ",b);
printf(" \ n ");
}