Exponents is the number of times you will multiply the number to itself
ex. 2^3
3 is the exponent meaning 2^3 = 2 x 2 x 2
you will multiply 2 by itself 3 times
radicals imaginary numbers occurs when a negative integer is inside a rooted value
ex.  \sqrt{-2}
its just the same as  \sqrt{2 * -1} where  \sqrt{-1} is i and i represents imaginary

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