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If four quantities are in proportion, they will be in proportion by COMPOSITION ; that is, the sum of the first and second, will be to the second, as the sum of the third and fourth, is to the fourth.
A Treatise on Algebra - Page 339
by George Peacock - 1830 - 685 pages

## An Elementary Treatise on Algebra: Theoretical and Practical

James Ryan - Algebra - 1824 - 548 pages
...third. XV. Componendo, by composition, when it is inferred that the sum of the first and second is to the second as the sum of the third and fourth is to the fourth. XVI. Dividendo, by division, when it is inferred that the excess of the first above the second is to...

## An Elementary Treatise on Algebra, Theoretical and Practical ...

James Ryan, Robert Adrain - Algebra - 1824 - 542 pages
...third. XV. Componendo, by composition, when it is inferred that the sum of the first and second is to the second as the sum of the third and fourth is to the fourth. XVI. Dividendo, by division, when it is inferred that the excess of the first above the second is to...

## The Practical Analyst: Or, A Treatise on Algebra, Containing the Most Useful ...

Enoch Lewis - Algebra - 1826 - 180 pages
...-=-= — bd bd о а 63. When four quantities are proportionals, the sum of the first and second is to the second, as the sum of the third and fourth is to the fourth. c+d r Or, a+6:o :: c+d: d. If the word difference be substituted for sum, the proposition will still...

## Elements of Geometry: With Notes

John Radford Young - Euclid's Elements - 1827 - 246 pages
...viz. : — If four magnitudes be proportional, the sum of the first and second will be to the first or second as the sum of the third and fourth is to the third or fourth. EE A ! BA ! B -D Let AE be to EB as CF is to FD ; then will AB be to BE, or AE, as...

## Elements of Geometry: Being Chiefly a Selection from Playfair's Geometry

John Playfair - Geometry - 1829 - 210 pages
...A : C : : B : D (33). ' 37. If four quantities be proportional, the sum of the first and second is to the second, as the sum of the third and fourth is to the fourth. A i^B* ::C +:1?' Den ^ comPosition) For *=-?, and * «J? - . A+g C + D B D' BD ' ' ' ^S~ " " D •>...

## The student's algebra

John Darby (teacher of mathematics.) - 1829 - 212 pages
...other product the means. 3. If four quantities be proportionals, the sum of the first and second is to the second, as the sum of the third and fourth is to the fourth. Thus, if a;b; ;c'd, then will a+b:by.c+d;d. 4. If four quantities be proportionals, the difference...

## Geometry, Plane, Solid, and Spherical, in Six Books: To which is Added, in ...

Pierce Morton - Geometry - 1830 - 584 pages
...be proportionals, they shall also be proportionals when taken conjointly ; that is, the sum of the first and second shall be to the second, as the sum of the third and fourth to the fourth : or, compo nendo, A + B:B::C + D: D. For, if any like parts whatever, as the nth, of...

## Library of Useful Knowledge: Geometry plane, solid, and spherical [by Pierce ...

Mathematics - 1835 - 684 pages
...be proportionals, they shall also be proportionals when taken conjointly ; that is, the sum of the first and second shall be to the second, as the sum of the third and fourth to the fourth : or, componendo, A + B: В : : C + D: D. For, if any like parts whatever, as the иш,...