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My problem is:

4 sqrt 81
I know the answer is 3, but I do not know how they got it.

• Algebra Help Radical notation -

write that as 81^(.25) which is (81^.5)^.5

that is
sqrt ( sqrt 81 )
81 is nine times nine
so
sqrt ( sqrt 81 ) = sqrt (9)
but 9=3*3 so
sqrt (9) = 3

• Algebra Help Radical notation -

Thank-you, I don't know why I did not think of that. I came up with every other number imaginable but that. I think I was trying toooooooooooooo hard!

• Algebra Help Radical notation -

• Algebra Help Radical notation -

(-64)^2/3

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