 | John Marsh (writing-master.) - 1742 - 238 Seiten
...12, as 7 is to 28 ; or 3 is to 7, a» i2 is to 28. And when four Numbers.are thus Proportional, then the Product of the Means is equal to the Product of the Extreams. For 12x7=84 the Product of the Means. And 3x28=84 the Product of the Extreams. Wherefore... | |
 | Daniel Fenning - 1802 - 274 Seiten
...in .if., either continued or interrupted (provided the interruption be between the 2d and 3d term), the product of the means is equal to the product of the extremes. EXAMPLE. Let the 4 numbers be 5, 15, 26, and 78 interrupted; then 5 x 78 = 15 x 26= 390. It will be... | |
 | Isaac Dalby - 1806 - 526 Seiten
...ac Or thus, since - z= -. • ba and f = > therefore 1=7. hdbh 68. If 4 quantities are proportional, the product of the means is equal to the product of the extremes. Thus suppose a : b : : c : d Then ad = he. For ? = ^ (s+)i and multiplying both fractions by W we have... | |
 | Zadock Thompson - 1828 - 238 Seiten
...second nomher to their price, and this must he ohvious from what was said in article 191. 195. Since, in every proportion, the product of the means is equal to the product of the extremes, one of these products may he taken for the other. Now if we divide the product of the means hy one... | |
 | John Darby (teacher of mathematics.) - 1829 - 212 Seiten
...are read, a is to b as c to d; therefore -r- = —r 2. When four quantities are proportionals, tha product of the means is equal to the product of the extremes ; that is, if a ; b ; ' c ; d, then will ad = be. Also, if a ; 6 ; rb ; c, then will ac = 62. Whence... | |
 | Oliver A. Shaw - 1832 - 112 Seiten
...The other principles of the doctrine of proportion may also be demonstrated; as the proposition that the product of the means is equal to the product of the extremes, proportion by alternation, or that if the first term be to the second as the third is to the fourth,... | |
 | Zadock Thompson - 1832 - 182 Seiten
...product of the first and fourth equals the product of the second and third, or, in other words, that the product of the means is equal to the product of the extremes. 194. In the proportion, 4 : 6 : : 12 : 18, the order of the terms may be altered without destroying... | |
 | Zadock Thompson - 1832 - 186 Seiten
...product of the first and fourth equals the product of the second and third, or, in other words, that the product of the means is equal to the product of the may stand, 4 : 12 : : 6 : 18, or 18 : 12 : : 6 : 4, or 18 : 6 :": 12 • 4 or 6 : 4 : : 18 : 12, or... | |
 | Francis Joseph Grund - 1833 - 224 Seiten
...; (because 450 — г is A's gain, and 450 — (500 — x) = — 50 -f- x is B's gain,) and because the product of the means is equal to the product of the extremes, 450,000 — 900 x — 1,000 x -j- 2 x2 = 5 z2 — 250 *. This equation, when reduced, may be written... | |
 | Dionysius Lardner - 1834 - 378 Seiten
...found. (379-) Since four numbers, which are in proportion, will continue to be in proportion so long as the product of the means is equal to the product of the extremes, it follows that we may make any of the following changes in the order of the four terms, without destroying... | |
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In any proportion, the product of the means is equal to the product of the extremes. 
