PURE YEAR 2 Flashcards
how can a rational number be expressed
a/b
a and b are integers
in an arithmetic sequence what is constant
the difference between consecutive terms
formula for nth term of arithmetic sequence
un= a + (n-1) d
formula for first n terms of an arithmetic sequence
Sn= n/2 (2a + (n-1) d)
a geometric sequence has what
a common ratio between consecutive terms
formula for nth term of geometric sequence
un = a r^(n-1)
formula for sum of first n terms of geometric sequence
Sn= (a (1-r^n) / 1-r)
OR
Sn= (a (r^n - 1)/ r-1)
when is a geometric sequence convergent
|r|<1
sum to infinity of a geometric sequence
a / 1-r
when can you sum to infinity
when a geometric sequence is convergent
what is a recurrence relation
u (n+1) = f (u(n))
defines each term of a sequence as a function of the previous term
when is a sequence increasing
u(n+1) > u(n) for all n
when is a sequence decreasing
u(n+1) < u(n) for all n
when is a sequence periodic
if the terms repeat in a cycle
for a periodic sequence there is an integer k such that u(n+k) = u(n) for all n
the value k is called the order of the sequence
radian to degrees
x 180/pi
degrees to radians
x pi/180
arc length equation
l= θr
radius x angle (in radians)
sector area equation
1/2 r^2 θ
(in radians)
segment area equation
1/2 r^2 (θ - sinθ)
when θ is small and measured in radians:
approximation for sinθ
θ
when θ is small and measured in radians:
approximation for tanθ
θ
when θ is small and measured in radians:
approximation for cosθ
1 - θ^2 / 2
sec x =
1 / cos x
cosec x =
1 / sin x
cot x =
1 / tan x
OR
cos x / sin x
equation for binomial expansion applied to negative/fractional values of n to obtain infinite series?
(1+x)^n
1 + nx + (n(n-1)x^2)/2! + (n(n-1)(n-2)x^3)/3! + … + (nCr) x^r
when is year 2 binomial expansion equation valid
when |x|<1
when is the expansion os (1+bx)^n (where n is negative or a fraction) valid
valid for |bx|<1