To find the nonpermissible replacement for y in the expression;
[tex]\frac{y+3}{y-1}[/tex]The nonpermissible replacement for y is the replacement for y at which the denominator of the expression is zero. (when the denomenator is zero, the final value can not be determined).
For the given expression, the denomenator is;
[tex]y-1[/tex]For y to be nonpermissible, the denometor must be equal to zero.
[tex]y-1=0[/tex]To get y, add 1 to both sides.
[tex]\begin{gathered} y-1+1=0+1 \\ y=1 \end{gathered}[/tex]At y =1, the expression becomes;
[tex]\frac{y+3}{y-1}=\frac{1+3}{1-1}=\frac{4}{0}\rightarrow\text{ nonpermissible }[/tex]Therefore, the nonpermissible replacement for y in the given expression is;
[tex]y=1[/tex]