The rational function is defined as a polynomial of two parts. That is numerator and denominator i.e., denominator should not be zero.
Explanation:
The given function is f(x)=13/10-x
Step:1
apply values to the term x in the given function,
Take X=1,
the equation becomes
f(1)=13/10-1
f(1)=1.444
Take X=2,
the equation becomes,
f(2)=13/10-8
f(2)=1.625
similarly,
f(3)=1.857,
f(4)=2.167,
f(5)=2.60,
f(6)=3.25,
f(7)=4.33,
f(8)=6.50,
f(9)=13,
but for f(10)= 13/10-10
f(10)=∞
f(11)=-13,
f(12)=-6.5,
f(13)=4.33,.. etc
so, f(x) is positive when the X value is less than 10.
f(x) is negative when the X value is more than 10.
but f(10)=∞ is never possible
Therefore, all the numbers are correctly apted expect zero