1 | Sums, logarithms, derivatives Flashcards
Terminology - name all parts of a summation
eg
Σ1 ≤ k ≤ n a
Σ = Sigma
1 = lower bound
k = index
n = upper bound
a = formula
a_k = term / summand
Summation for odd numbers
Σ0 ≤ k ≤ n (2k +1)
Summation for even numbers
Σ0 ≤ k ≤ n (2k)
True or false:
Σ1 ≤ k ≤ n ak = Σ0 ≤ k ≤ n-1 ak+1
True
(when in doubt — expand!)
True or false:
Σ1 ≤ k ≤ n ak =Σ1 ≤ k ≤ n ak + 1
False
(when in doubt — expand!)
True or false:
Σ2≤k≤n-1 k(k-1)(n-k) = Σ0≤k≤n k(k-1)(n-k)
True
(when in doubt — expand!)
True or false:
Σ0 ≤ k ≤ n-1 ak+1 = Σ1 ≤ k ≤ n ak + 1
False
(when in doubt — expand!)
True or false:
Σ1≤k≤n 2(k+1) = 2Σ1≤k≤n (k+1)
True
(Distributive law)
True or false:
Σ1≤k≤n (k+1) = Σ1≤k≤n k + Σ1≤k≤n 1
True
(Associative law)
Commutative law?
Σk∈K ak = Σp(k)∈K ak
𝑎1 + 𝑎2 + 𝑎3 = 𝑎2 + 𝑎1 + 𝑎3 = 𝑎3 + 𝑎1 + 𝑎2
Arithmetic progression - generic formula?
S = Σ0≤k≤n (a + bk)
Arithmetic progression - describe with words and a formula
an - an-1 = b
Whenever subtracting 2 adjacent terms, the solutions is a constant, b
Arithmetic progression - closed form solution
S = Σ0≤k≤n (a + bk)
(2a + bn)(n + 1)/2
∩ symbol?
Intercept - all elements that are common between two sets
∪ symbol?
Union - two sets combined
Manipulation of sums
Σk∈K ak + Σk∈K’ ak = ?
Σk∈K∩K’ ak + Σk∈K∪K’ ak
Example of perturbation method?
Σ0≤k≤n ak = a0 + Σ1≤k≤n ak
= operation of splitting off a term
Geometric progression - generic formula
Sn = Σ0≤k≤n axk
Geometric progression - describe with formula and words
an / an-1 = q
Whenever dividing 2 adjacent terms, the resulting ratio is always a constant, q
Geometric progression
Sn = Σ0≤k≤n axk
closed form solution?
(𝑎 − 𝑎𝑥𝑛+1)/(1 − x)
Σ1≤k≤nc = ?
nc
Σ1≤k≤nk
n(n+1)/2
Σ1≤k≤nk2
n(n+1)(2n+1)/6
What is the rule for multiple sums?
Which sum is calculated first?
ΣP(j,k)ajbk
= Σj,kajbk I[P(j,k)]
= ΣjΣkajbkI[P(j,k)]
innermost sum first
Logarithms
logbx = y
x = ?
x = by
Logarithms
Product rule
logbxy
= logbx
+ logby
Logarithms
logbxy
= ?
= logbx
+ logby
Logarithms
Quotient rule?
logbx/y
= logbx
- logby
Logarithms
logbx
- logby = ?
logbx/y
Logarithms
Power rule?
logbxp
= p*logbx
Logarithms
logbxp</sup =?
= p*logbx
Logarithms
1/p*logbx
logb(pth root of x)
Logarithms
Change of base rule?
logbx
= logkx / logkb
Derivatives
f(x) = ex
f’(x) = ?
ex
Derivatives
f(x) = ax
axln(a)
Derivatives
f(x) = ln(x)
f’(x) = ?
1/x
Derivatives
f(x) = logax
f’(x) = ?
1/xln(a)
Derivatives
f(x) = ag(x) + bh(x)
f’(x) = ?
ag’(x) + bh’(x)
Derivatives
f(x) = g(x)*h(x)
f’(x) = ?
g’(x)h(x) - g(x)h’(x)
Derivatives
f(x) = g(x)/h(x)
f’(x) = ?
[ g’(x)h(x) - g(x)h’(x) ] / (h(x))2
Derivatives
f(x) = h(g(x))
f’(x) = ?
h’(g(x))g’(x)