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If the product of two quantities is equal to the product of two others, the...
An Elementary Geometry - Page 27
by William Frothingham Bradbury - 1872 - 110 pages

## A treatise on the elements of algebra, by G. Ainsworth and J. Yeats

G. Ainsworth - 1854 - 216 pages
...d, then -=-, and multiplying both sides by ac, —= — , Л С ' <to . • . bc=ad. And conversely, if the product of two quantities is equal to the product of two other quantities, the four are proportional. For (by hyp.) ad=bc, and dividing both sides by bd, we...

## A Treatise on Algebra

Elias Loomis - Algebra - 1855 - 356 pages
...expression becomes abd bcd ~b~=~d' or ad=bc. Thus, if 3 : 4 : : 9 : 12, .hen 3X12=4X9. (213.) Conversely, if the product of two quantities is equal to the product of two others, the first two quantities may be made the extremes, and the other two the means of a proportion. Let- ad=bc....

## Mathematical Dictionary and Cyclopedia of Mathematical Science: Comprising ...

Charles Davies, William Guy Peck - Mathematics - 1855 - 628 pages
...definition, that the product of the extremes is equal to the product of the menus ; and conversely, if the product of two quantities is equal to the product of two others, the first two may be taken as the structed with a groove in each leg, so that extremes, and the last two...

## The Popular Educator, Volume 6

1855 - 424 pages
...means in both cases is the same. So, if na : Ь : : x : y, then a : Ь : : x : ny. On the other hand, if the product of two quantities is equal to the product of two others, the four quantities will form a proportion, if they are so arranged that those on one side of the equation...

## Elementary Treatise on Algebra

Thomas Sherwin - Algebra - 1855 - 318 pages
...product of the extremes. 2. Suppose we have ad=bc. Dividing both members by b XLIX. PROPORTIONS. 221 If the product of two quantities is equal to the product of two otner quantities, the two factors of either product may be made the means, and the two factors of the...

## Common School Algebra

Thomas Sherwin - Algebra - 1855 - 262 pages
...ad=bc. If we divide both members by b and d, we have — = —, or bdi a : b = c : d. Therefore, •• If the product of two quantities is equal to the product of two other quantities, the two factors of one product may be made the means, and the two factors of the...

## The Elements of Algebra

Elias Loomis - Algebra - 1856 - 280 pages
...the equation of fractions, we have ad— bc. Thus, if 3:4:: 9:12, then 3x12=4x9. (184.) Conversely, if the product of two quantities is equal to the product of two others, the first two quantities may be made the extremes, and the other two the means of a proportion. Let ad=bc...

## Mathematical Dictionary and Cyclopedia of Mathematical Science: Comprising ...

Charles Davies, William Guy Peck - Mathematics - 1857 - 608 pages
...portional to the other three taken in their ^ of the means ; and conversely, if the product order. j of two quantities is equal to the product of two others, the first two may be taken as the extremes, and the last two as the means, of a proportion. PROPORTION....