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The sum of any number of terms is equal to the sum of the extremes multiplied by half the number of terms.
Elements of algebra, by A. Ingram and J. Trotter - Page 70
by Alexander Ingram - 1844

## The National Arithmetic on the Inductive System: Combining the Analytic and ...

Benjamin Greenleaf - Arithmetic - 1858 - 458 pages
...the sum of the series must equal half the sum of the extremes multiplied by the number of terms, or the sum of the extremes multiplied by half the number of terms. RULE. — Multiply half the sum of the extremes by the number of terms. Or, Multiply the sum of the...

## The National Arithmetic on the Inductive System: Combining the Analytic and ...

Benjamin Greenleaf - Arithmetic - 1858 - 456 pages
...the sum of the series must equal half the sum of the extremes multiplied by the number of terms, or the sum of the extremes multiplied by half the number of terms. RULE. — Multiply half the sum of the extremes l»j the number of terms. Or, Multiply the sum of the...

## University Algebra : Embracing a Logical Development of the Science with ...

Charles Davies - Algebra - 1860 - 332 pages
...Here, (a+l) is taken n times ; hence, 2s = n(a+l) ; or, s — %n(a+T) . . (2.) That is, the sum of the terms is equal to the sum of the extremes, multiplied by half the number of terms. Formula ( 2 ) can be placed under another form, by substituting for I its value taken from Formula...

## Practical Arithmetic: Embracing the Science and Applications of Numbers

Charles Davies - Arithmetic - 1863 - 346 pages
...and 19, taken as many times as there are terms; and the given series is equal to half this sum, or to the sum of the extremes multiplied by half the number of terms. Rule. — Add the extremes together, and multiply their sum by half the number of terms ; the product...

## Plane and spherical trigonometry. [With] Solutions of problems. [Followed by ...

Henry William Jeans - 1873 - 292 pages
...reduce arithmetical and algebraical expressions to logarithms* (22). (a) The logarithm of the product of any number of terms is equal to the sum of the logarithms of all the terms in the product : Thus, if x=ab, then log. a:=log. a + log. b (b) The logarithm...

## Manual of Algebra

William Guy Peck - Algebra - 1875 - 348 pages
...(a + 1) is taken n times ; hence, 2s = n(a + 1); or, s = %n(a + I), . . (2) that is, the sum of the terms is equal to the sum of the extremes, multiplied by half the number of terms. Formula (2) can be placed under another form, by substituting for I its value taken from formula (1):...

## Complete Arithmetic Combining Oral and Written Exercises

Indiana. State Board of Education - 1886 - 360 pages
...4 25 7 22 10 19 13 10 16 13 19 10 22 7 25 4 It follows, therefore, that the sum of a series equals the sum of the extremes multiplied by half the number of terms. 7. If the first term of a decreasing series is 100 and the common difference 3, what is the 32d term...