Answer
$1$
Work Step by Step
Add $1$ to both sides:
$4\sqrt {x}-1+1=3+1$
$4\sqrt {x}=4$
Divide $4$ to both sides:
$\dfrac{4\sqrt {x}}{4}=\dfrac{4}{4}$
$\sqrt {x}=1$
Square both sides.
$\left(\sqrt {x}\right)^2=1^2$
$x=1$
Substitute into original problem to check for extraneous solutions:
$4\sqrt {(1)}-1=3$
$4(1)-1=3$
$4-1=3$
$3=3$