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Inconvenience of the successive elimination of the unknown
quantities when there are more than two equations and in-
dication of the degree of the final equation

198

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Every equation, the coefficients of which are entire numbers,
that of the first term being 1, can only have for roots en-
tire numbers or incommensurable numbers
Method of clearing an equation of fractions
Investigation of commensurable divisions of the first degree 202
How to obtain the equation, the roots of which are the differ-
ences between one of the roots of the proposed equation
and each of the others

205

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Note-respecting equal roots.

To prove the existence of real and unequal roots

Use of division of roots for facilitating the resolution of an equa-

tion when the coefficients are large

Method of approximation according to Lagrange

Of Proportion and Progression

Fundamental principles of proportion and equidifference

Of the changes which a proportion may undergo

Of progression by differences

To determine any term whatever of this progression

To determine the sum of the terms

Of progression by quotients

General term.

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In what cases the quotient of this operation is converging and may

be taken for the approximate value of the fraction

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ELEMENTS OF ALGEBRA.

Preliminary Remarks upon the Transition from Arithmetic to Algebra-Explanation and Use of Algebraic Signs.

1. It must have been remarked in the Elementary Treatise of Arithmetic, that there are many questions, the solution of which is composed of two parts; the one having for its object to find to which of the four fundamental rules the determination of the unknown number by means of the numbers given belongs, and the other the application of these rules. The first part, independent of the manner of writing numbers, or of the system of notation, consists entirely in the development of the consequences which result directly or indirectly from the enunciation, or from the manner in which that which is enunciated connects the numbers given with the numbers required, that is to say, from the relations which it establishes between these numbers. If these relations are not complicated, we can for the most part find by simple reasoning the value of the unknown numbers. In order to this it is necessary to analyze the conditions, which are involved in the relations enunciated, by reducing them to a course of equivalent expressions, of which the last ought to be one of the following; the unknown quantity equal to the sum or the difference, or the product, or the quotient, of such and such magnitudes. This will be rendered plainer by an example.

To divide a given number into two such parts, that the first shall exceed the second by a given difference.

In order to this we would observe 1, that,

The greater part is equal to the less added to the given excess, and that by consequence, if the less be known, by adding to it this excess we have the greater; 2, that,

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