A First Book in Algebra by Wallace C. Boyden 1895

"162. A root which can be found exactly is called an exact or

rational root. Such roots are either whole numbers or fractions.

A root which is indicated but can be found only approxi-

mately is called a surd. Such roots involve the roots of imperfect

powers.

Rational and surd roots are together called real roots.

A root which is indicated but cannot be found, either exactly

or approximately, is called an imaginary root. Such roots in-

volve the even roots of negative numbers."

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