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What is the
of 17,1 ? What is the square of ,085 ? What is the cube of 25,4 ? What is the biquadrate of 12? What is the
of 71 ?
EVOLUTION, OR EXTRACTION OF ROOTS. WHEN the root of any power is requis ed, the business of finding it is called the Extraction of the Root.
The root is that number, which by a continual multiplication into itself, produces the given power.
Although there is no number but what will pruduce a perfect power by involution, yet there are many numbers of which precise roots can never be determined. But, by the help of decimals, we cån approximate toward the root to any assigned degree of exactness.
The roots which approximate, are called surd roots, and those which are perfectly accurate are called.rational roots.
A table of the Squares and Cubes of the nine digils. Roots. | 1 | 2 | 3 | 41 5 66 7 8 9
Squares. | 1 | 4 | 9 | 16 | 25 | 36 49 641 81, (Cubes. 1118 | 27 | 64 | 125 | 216 343] 512| 729
EXTRACTION OF THE SQUARE ROOT.
To extract the square root, is only to find a number, which being multiplied into itself shall produce the given number:
RULE. 1. Distinguish the given number into periods of two figures each, by putting a point over the place of units, another over the place of hundreds, and so on; and if there are decimals, point them in the same manner, from units toward the right hand; which points show the number of figures the root will consimt ci.
2 Find the greatest tune med pip lantes
hand period, place the root of it at the right hand of the given number, (after the manner of a quotient in di. vision) for the first figure of the root, and the square number under the period, and subtract it therefrom, and to the remainder bring down the next period, for a divi. dend.
3. Place the double of the root, already found, on the left hand of the dividend for a aivisor.
4. Place such a figure at the right hand of the divisor, and also the same figure in the rcot; a3 when multipiied into the whole (increased divisor) the product shall be equal to, or the next less than the dividend, and it will be the second figure in the root.
5. Subtract the product from the dividend, and to the remainder join the next period for a new dividend.
6. Double the figures already found in the root, for a new divisor, and from these find the next figure in the root as last directed, and continue the operation in the same manner, till you have brought down all the periods.
Or, to facilitate the foregoing rule, when you have brought down a period, and formed a dividend in order to find a new figure in the root, you may divide said divi vend, (omitting the right hand figure thereof,) by dcuble the root already found, and the quotient will commonly be the figures sought, or being made less one or two, will generally give the next figure in the quotient.
1. Required the square rout of 141225,64. 141225,64(375,8 the root exactly without a remain 9
der ; but when the periods belong
ing to any given number are ex 67)512
hausted, and still leave a remain 469
der, the operation may be contin
ued at pleasure, by annexing pe. 745)4325
risis of cyphers, &c. 3725
2. What is the square root of 1296 ? 3. Of
56644 ? 4. Of
5499025 ? 5. Of
36372691 ? 6. Of
184,2 ? 7. Of
9712,693809? 8. Of
0,45369? 9. Of
,002916 ? 10. Of
36 23,8 2345 6031 13,57+ 98,553
,673+ ,054 6,708+
TO EXTRACT THE SQUARE ROOT
RULE. Reduce the fraction to its lowest terms for this and all other roots; then
i. Extract the root of the numerator for a new numerator, and the root of the denominator, for a new denominator.
2. If the fraction be a surd, reduce it to a decimal, and extract its root.
EXAMPLES 1. What is the square root of it? Answers, $ 2. What is the square root of the
? 3. What is the square root of 17 ? 4. What is the square root of 201?
4. 5. What is the square root of 248, ? 15%
SURDS. 6. What is the square root of ?
91284 7. What is the square root of 4 !
,7745+ 8. Required the square root of 367 ? 6,0207+ APPLICATION AND USE OF THE SQUARE
ROOT. PROBLEM I. A certain General has an army of 5184 men; how many must he place in rank and file to foruma them into a square ?
V5184572 Ans. Prob. II. A certain square pavement contains 20736 square stones, all of the same size ; I demand how many are contained in one of its sides? V 20736=144 Ans.
PROB. III. To find a mean proportional between twe numbers.
RULE. Multiply the given numbers together, and extract the square root of the product. What is the mean proportional between 18 and 72 ?
72x18=1297, and V 1296=36 Ans. PROB. IV. To form any body of soldiers so that they may be double, triple, &c. as many in rank as in file.
RULE. Extract the square root of 1-2, 1-3, &c. of the given number of men, and that will be the number of men in file, which double, triple, &c. and the product will be the number in rank.
Let 13122 men be so formed, as that the number in rank may be double the number in file.
13122-2=6561, and V6561=81 in file, and 81 X2 162 in rank.
Prob. V. Admit 10 hhds. of water are dischargea through a leaden pipe of 2 inches in diameter, in a certain time; I demand what the diameter of another pipe must be to discharge four times as much water in the same time.
RULE. Square the given diameter, and multiply said square by the given proportion, and the square root of the pro duct is the answer. 21=2,5, and 2,5 X 2,5=6,25 square.
4 given proportion.
55,00-inch. diam. Ans
PROB. VI. The sum of any two numbers, and their products being given, to find each number.
product, and extract the square root of the remainder, which will be the difference of the two numbers; then half the said difference added to half the sum, gives the greater of the two numbers, and the said half difference subtracted from the half sum, gives the lesser number.
EXAMPLES The sum of two numbers is 43, and their product is 442; what are those two numbers?
The sum of the numb. 43x43=1849 square of do. The product of do. 442X 41768 4 times the pro. Then to the sum of 21,5
81=9 diff. of the
EXTRACTION OF THE CUBE ROOT, A cube is any number multiplied by its square.
To extract the cube root, is to find a number, which, being multiplied into its square, shall produce the given number.
RULE. 1. Separate the given number into periods of three figures each, by putting a point over the unit figure, and every third figure from the place of units to the left, and if there be decimals, to the right.
2. Find the greatest cube in the left hand period, and place its root in the quotient.
3. Subtract the cube thus found, from the said period, and to the remainder bring down the next period, calling this the dividend.
4. Multiply the square of the quotient by 800, calling it the divisor.