Question

x^2-4x=21 solve by completing the square

Answer 1

\[x^2-4x=21\] half of 4 is 2, and 2 squared is 4 so write
\[(x-2)^2=21+4\]
\[(x-2)^2=25\]
therefore \(x-2=5\) or \(x-2=-5\)
first equation gives \(x=7\) second gives \(x=-3\)

Answer 2

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