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urp:algebra [2021-11-08] nerf_herder |
urp:algebra [2022-02-01] (current) nerf_herder [Arithmetic Sequences] |
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| ====Algebra & Pre-Calc==== | ====Algebra & Pre-Calc==== | ||
| + | Related pages: | ||
| * [[Graphing|Graphing circles, ellipses, parabolas, hyperbolas]] | * [[Graphing|Graphing circles, ellipses, parabolas, hyperbolas]] | ||
| * [[poly|Polynomials, quadratic formula and completing the square]] | * [[poly|Polynomials, quadratic formula and completing the square]] | ||
| + | * [[power|Powers, radicals (roots) & logs]] | ||
| **quadratic formula**: x = (-b ±√(b²-4ac)) / 2a | **quadratic formula**: x = (-b ±√(b²-4ac)) / 2a | ||
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| https://courses.lumenlearning.com/suny-osalgebratrig/chapter/parametric-equations/ | https://courses.lumenlearning.com/suny-osalgebratrig/chapter/parametric-equations/ | ||
| - | ==== Arithmetic Sequences ==== | + | ==== Arithmetic/Geometric Sequences ==== |
| + | |||
| + | **Arithmetic sequence** has a constant difference between the terms, such as 1, 3, 5, 7, 9... | ||
| Basic form to find term n: a(n) = a(1) + d(n-1), where d = step size (difference between terms), a(1) is the first term | Basic form to find term n: a(n) = a(1) + d(n-1), where d = step size (difference between terms), a(1) is the first term | ||
| Line 45: | Line 48: | ||
| S = n/2 (2a + (n − 1) d) | S = n/2 (2a + (n − 1) d) | ||
| - | ==== Powers & Radicals ==== | + | **Geometric sequence** terms are found by multiplying the previous term by a constant, such as 2, 4, 8, 16 ... |
| - | Combining powers | + | a(n) = arⁿ⁻¹ |
| - | nᵃnᵇ = nᵃ⁺ᵇ | + | |
| - | nᵃ/nᵇ = nᵃ⁻ᵇ | + | |
| - | (nᵃ)ᵇ = nᵃᵇ | + | |
| - | n⁻ᵃ = 1/nᵃ | + | |
| - | (Note: The square root sign, √, refers only to the //positive// root. Use ± to include both roots.) | + | Other sequences exist: |
| + | * squares: a(n) = n², cubes, etc. | ||
| + | * triangular numbers: a(n) = n(n+1)/2 (number of dots in a triangle of n rows) | ||
| + | * fibonacci sequence: a(n) = a(n-1) + a(n-2) | ||
| - | Factorial: | + | Convergence of a power sequence: http://math.bu.edu/people/prakashb/Teaching/32LS10/Lectures/11-2.pdf |
| + | ====Factorial==== | ||
| n! = n * (n-1)! | n! = n * (n-1)! | ||
| 0! = 1 | 0! = 1 | ||
| 7!/(7-3)! = 7!/4! = 7*6*5 * (4!/4!) = 7*6*5 | 7!/(7-3)! = 7!/4! = 7*6*5 * (4!/4!) = 7*6*5 | ||
| - | |||
| - | |||
| - | ==== Logs ==== | ||
| - | |||
| - | Log is the inverse of a power | ||
| - | x = bᵉ, e = logᵦ(x) (b = base, 10 by default) | ||
| - | eg. 2³ = 8, log₂(8) = 3 | ||
| - | log(1) = 0 (for any base), log(x) is undefined for x =< 0 | ||
| - | logₐ(x) = logᵣ(x) / logᵣ(a) | ||
| - | = log(x) / log(a) for r=10 | ||
| - | = ln(x) / ln(a) for r=e (e = Euler's number, 2.718..) | ||
| - | ln(e) = 1, log(10) = 1 | ||
| - | ln(x) = logₑx. | ||
| - | eᵏ = c, and k = ln(c) => e^ln(c) = c | ||
| - | |||
| - | a^logₐ(x) = x (power and log are inverses, cancel each other out) | ||
| - | logₐ(aᵏ) = k (same reason) | ||
| - | product rule: log(ab) = log(a) + log(b) | ||
| - | quotient rule: log(a/b) = log(a) - log(b) | ||
| - | power rule: log(aᵇ) = b*log(a) | ||
| ==== Functions ==== | ==== Functions ==== | ||
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| Graphing an inverse: reflection of the graph about the line y=x | Graphing an inverse: reflection of the graph about the line y=x | ||
| - | **horizontal and vertical asymptotes:** | + | **asymptotes** |
| y = (quadratic1 of x) / (quadratic2 of x) | y = (quadratic1 of x) / (quadratic2 of x) | ||
| * vertical asymptotes (VA) are when denominator goes to zero | * vertical asymptotes (VA) are when denominator goes to zero | ||
| * horizontal asymptotes (HA) is when x goes to infinity, look at highest order of x in numerator and denominator: | * horizontal asymptotes (HA) is when x goes to infinity, look at highest order of x in numerator and denominator: | ||
| * y = axⁿ / bxᵏ | * y = axⁿ / bxᵏ | ||
| - | * if n > k : no HA | ||
| * if n < k : HA = 0 | * if n < k : HA = 0 | ||
| * if n = k : HA = a/b | * if n = k : HA = a/b | ||
| + | * if n > k : no HA | ||
| + | * if n = k+1 : oblique (diagonal) asymptote - approaches the line y = mx+b (from polynomial long division) | ||
| + | * if n > k+1 : no asymptote | ||
| + | |||
| + | look halfway down the page here: https://www.mathsisfun.com/algebra/rational-expression.html | ||
| ====Interest, half life, amortization==== | ====Interest, half life, amortization==== | ||
urp/algebra.1636395142.txt.gz · Last modified: 2021-11-08 by nerf_herder
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