Any two of the quantities x + y, x^2 + y^2, xy, x^3 + y^3,
x^3 - y^3, x - y, x^2 +- xy + y^2, etc., given.
x^2 + y^2 = 41,
x + y = 9.
CASE IV.
Both equations symmetrical or symmetrical except for sign.
Usually one equation of high degree, the other of the first
degree.
x^5 + y^5 = 242,
x + y = 2.
CASE V. Special Devices
I. Solve for a compound unknown, like xy, x + y, (1)/(xy),
etc., first.
x^2y^2 + xy = 6,
x + 2y = -5.
II. Divide the equations, member by member.
x^4 - y^4 = 20,
x^2 - y^2 = 5.
III. Eliminate the quadratic terms.
4x + 3y = 2xy,
7x - 5y = 5xy.
~Ratio and Proportion~
Proportionals
mean,
third,
fourth.
Theorems
1. Product of means equals product of extremes.
2. If the product of two numbers equals the product of two
other numbers, either pair, etc.
3. Alternation.
4. Inversion.
5. Composition.
6. Division.
7. Composition and division.
8. In a series of equal ratios, the sum of the antecedents
is to the sum of the consequents as any antecedent, etc.
Special method of proving four quantities in proportion. Let
a/b = x, a = bx, etc.
~Progressions~
Development of formulas.
{ l = ar^(n - 1).
{ l = a + (n - 1)d. { S = (ar^n - a)/(r - 1).
{ S = (n/2)(a + l). { S = (rl - a)/(r - 1).
{ S = (n/2)[2a + (n - 1)d]. { S[infinity] = (a)/(1 - r).
Insertion of means
Arithmetical.
Geometrical.
~Binomial Theorem~
Review of binomial theorem laws. See Involution.
Expansion of (a + b)^n.
Finding any term by
key number method.
r^(th) or (r + 1)^(th) term method.
A REVIEW OF ALGEBRA
ORDER OF OPERATIONS, EVALUATION, PARENTHESES
Order of operations:
First of all, raising to a power and extracting a root.
Next, multiplication and division.
Last of all, addition and subtraction.
Find the value of:
1. 5 . 2^2 - 25^(1/2) / 5 + 2^2 . 8 / 4 - 2.
2. (3 x 6 / 9)/2 - 2[100^(1/2)] / 5 + 4 . 2^3 - (14 . 2)/28.
3. 9 . 2 / 6 + 3 - 2 . 4^2 / 8^(1/3) - 4 + (3 . 2^2)/6.
Evaluate:
4. (a^4 - a^3 + b^3)/([a^2 b^2]^(1/2)) + (c[a^(1/2)] + a^3bc)/(abc),
if a = 1, b = 2, c = 3.
5. t^(1/3) + [tm]^(1/3) + m^(1/3), if t = 8, m = 27.
6. (2[3 + 2d + a]^(1/2))/(3[a + b - cx - c]^(1/2))
+ ((3c - d)x)/(7ad - [abc]^(1/2)), if
a = 5, b = 3, c = -1, d = -2, x = 0.
7. a - {5b - [a - (3c - 3b) + 2c - 3(a - 2b - c)]},
if a = -3, b = 4, c = -5. (_Yale._)
Simplify:
8. m - [2m - {3r - (4r - 2m)}].
9. 2a - [5d + {3c - (a + [2d - 3a + 4c])}].
10. 3c^2 + c(2a - [6c - {3a + c - 4a}]).
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