Page:Elementary algebra (1896).djvu/21

Rh the coefficient of $$bc$$. A coefficient which is not merely numerical is sometimes called a literal coefficient.

7. A power of a quantity is the product obtained by repeating that quantity any number of times as a factor, and is expressed by writing the number of factors to the right of the quantity and above it. Thus,

$$a \times a$$ is called the second power of $$a$$, and is written $$a^2$$;

$$a \times a \times a$$ is called the third power of $$a$$, and is written $$a^3$$;

The index or exponent is the number which expresses the power of any quantity. Thus $$2$$, $$5$$, $$7$$ are respectively the indices of $$a^2$$, $$a^5$$, $$a^7$$.

8. The beginner must be careful to distinguish between coefficient and index.