Hi,

The first thing to do is to look at the integers in the expression and see if you can find factors that are squares. I see

125 = 5 25 = 5 5²

Also

16 = 4²

Thus the problem can be rewritten

sqrt(125 x 16) = sqrt( 5 5² x 4² )

Now take the square roots of the squares to get

sqrt( 5 5² x 4² ) = 5 4 sqrt(5 x) = 20 sqrt(5x)

Penny

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