Question 173695
well the way you have written it, 9 is not to the second power only x...and 2 is not to the 4th power only y....when you want to show the whole thing being raised to a power it must all be in parenthesis like {{{(2x)^2}}}
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{{{(4x)sqrt((9x)^2(2y)^4)}}}   since the square root of {{{x^2}}}is x and the 
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square root of {{{x^4}}}is {{{x^2}}}.....we are dealing with both of those here
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{{{(9x)^2}}}comes out as 9x and {{{(2y)^4}}}comes out as {{{(2y)^2}}}
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so {{{(4x)(9x)(2y)^2}}}={{{72x^2y^2}}}