Starting with the given equation, substract 11 from each member:
[tex]\begin{gathered} 11+\sqrt[]{1-3x}=15 \\ \Rightarrow11+\sqrt[]{1-3x}-1=15-11 \\ \Rightarrow\sqrt[]{1-3x}=4 \end{gathered}[/tex]Raise both members to the power of 2:
[tex]\begin{gathered} \Rightarrow(\sqrt[]{1-3x})^2=4^2 \\ \Rightarrow1-3x=16 \end{gathered}[/tex]Solve for x:
[tex]\begin{gathered} \Rightarrow-3x=16-1 \\ \Rightarrow-3x=15 \\ \Rightarrow x=\frac{15}{-3} \\ \Rightarrow x=-5 \end{gathered}[/tex]Therefore, the answer is:
[tex]undefined[/tex]
