How do you simplify the expression #sqrt3*3sqrt21#?

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Answer 1 · 2016-04-01T16:15:53

#9sqrt(7)#

Note that #3xx7=21#

So write the expression as:

#color(blue)(sqrt(3))color(brown)(xx3sqrt(3xx7))#

Combine the square roots

#3sqrt(3xx3xx7)#

#3sqrt(3^2xx7)#

Not that #sqrt(3^2)=3#

#3xx3sqrt(7)#

#9sqrt(7)#

#color(red)("Technically this could be "+-9sqrt(7))#