There are many videos on Khan Academy on this topic. You can find an expanded list here.
The videos assigned for class are below.
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Intro to square-root equations and extraneous solutions (11:09) Solve
.
Solving square root equations: one solution (3:10) Solve
.
Solving square root equations: two solutions (5:28) Solve
.
Solving square root equations: no solutions (3:58) Solve
.
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Extraneous solutions of radical equations (4:56) Find which values of
make
an extraneous solution for the equation
.
Solving cube root equations (3:34) Solve for
given
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Domain of a radical equation (1:48) Find the domain of