Books Books If four magnitudes are proportional, the sum of the first and second is to their difference as the sum of the third and fourth is to their difference. An Easy Introduction to the Mathematics: In which the Theory and Practice ... - Page 66
by Charles Butler - 1814 ## Elements of Geometry, Plane and Spherical: With Numerous Practical Problems

Horatio Nelson Robinson - 1869 - 276 pages
...between the third and fourth. THEOREM IX. If four magnitudes are proportional, the sum ojthe^first and second is to their difference as the sum of the third and fourth is to their difference. Let A, B, C, and D be the four magnitudes which give the proportion A : B ::... ## Algebra for the Use of Colleges and Schools: With Numerous Examples

Isaac Todhunter - Algebra - 1870 - 626 pages
...This operation is called convertendo. 396. When four quantities are proportionals, the sum of tlie first and second is to their difference as the sum of the third and fourth is to their difference. If a : b :: с : d, then a + b : ab :: c + d : c — d. By Art. 393, "v-^,... ## Algebra

Isaac Todhunter - 1870 - 818 pages
...This operation is called convertendo. 396. When four quantities are proportionals, the sum of tJte first and second is to their difference as the sum of the third and fourth is to their difference. If a : b :: с : d, then a + b : ab :: c + d : cd. a + bc + d By Art. 393,... ## Algebra for Beginners: With Numerous Examples

Isaac Todhunter - Algebra - 1872 - 356 pages
...b а а с а с or а-Ъ : a :: cd : c; therefore a : а-Ъ :: с : cd. 367. JVhenfbur numbers are proportionals, the sum of the first and second is to their difference as the »um of the third and fourth is to their difference; that is, if a : Ъ :: с : d, then a+b : а-Ъ... ## A Treatise on Algebra

Elias Loomis - Algebra - 1873 - 396 pages
...and we have a , c , ,, . a—b c—d that is, -£- = -^-, 306. If four quantities are proportional, the sum of the first and second is to their difference, as the sum of the third and fourth it to their difference. Let a : b : : c : d. By composition, Art. 304, a+b: b::c+d: d. By alternation,... ## A mathematical course for the University of London. (2nd)

Thomas Kimber - 1874 - 354 pages
...when a = 2 b : a , ab «* a*62 "r _ в _ 6* a* + 6* a* — b*' 7. Show that when> four numbers are proportionals, the sum of the first and second is...their difference as the sum of the third and fourth is to their difference. If a : b : : с : d, show that (a* + c*) (b" + d") = (ab + с d)2. 8. Find... ## The Complete Algebra: Designed for Use in Schools, Academies, and Colleges

Joseph Ficklin - Algebra - 1874 - 446 pages
...+ b : a = с + d : c, and a — b : a~ с — d : c; that is, If four quantities are in proportion, the sum of the first and second is to their difference as the sum of the third and fourth is to their difference. 436. TJie sum of any number of the antecedents of a continued proportion is... ## The Scholar's Algebra: An Introductory Work on Algebra

Lewis Hensley - Algebra - 1875 - 274 pages
...numbers into the sum of their squares into the sum of their fourth powers. (2) If four numbers are proportionals, the sum of the first and second is...the sum of the third and fourth to their difference. (3) A quantity consisting of the sum of the squares of three numbers and of twice the product of every... ## The Elementary Geometry of the Right Line and Circle ... With Exercises

William Alexander Willock - Circle - 1875 - 196 pages
...sums. BY COMPOSITION AND DIVISION. — When the first is to the second as the third to the fourth, the sum of the first and second is to their difference as the sum of the third and fourth is to their difference. This is a consequence of the preceding changes in the proportions, the submultiples... 