Start by substracting 19 on both sides
[tex]\begin{gathered} 4a^2+19=68 \\ 4a^2+19-19=68-19 \\ 4a^2=49 \end{gathered}[/tex]Continue by dividing by 4 on both sides
[tex]\begin{gathered} \frac{4}{4}a^2=\frac{49}{4} \\ a^2=\frac{49}{4} \end{gathered}[/tex]Finalize taking square root on both sides
[tex]\begin{gathered} \sqrt[]{a^2}=\sqrt[]{\frac{49}{4}} \\ a=\frac{7}{2} \end{gathered}[/tex]Check answer by replacing a into the first equation
[tex]\begin{gathered} 4\cdot(\frac{7}{2})^2+19=68 \\ 4\cdot(\frac{49}{4})+19=68 \\ 49+19=68 \\ 68=68 \end{gathered}[/tex]solution is correct.
