Given that
There are two equations and we have to find the value of b.
Explanation -
The two equations one is quadratic and the other is cubic. These are
b^2 = 4
and b^3 = 8
Now, on solving it we have
[tex]\begin{gathered} b^2=4 \\ b=\sqrt{4}=\sqrt{2\times2} \\ b=\pm2 \\ \\ b^3=8 \\ b=\sqrt[3]{8}=\sqrt[3]{2\times2\times2} \\ b=2 \end{gathered}[/tex]
So the correct option is A
Final answer - Therefore the answer is b^2 = 4
