rest of stewart Flashcards
Riemann sums
sum of f(x) delta x where f is a point in that area of delta x
definite integral
sum of the n riemmann sums as n aproaches infinity. each sum is of width delta x where delta x is (b-a)/n, x is then equal to a + i(b-a)/n. use summation properties
integral is equal to
lim as n aproaches infinity of the sum from i=0 to n of polynomial
midpoint rule
edtimation of area deltax X (F(x-) ….) where x is midpoint of the area of delta x
That one integration identitie with m and M
take m and M are the largest values of f in the given interval, then m(b-a) is greater or equal to integral is greater or equal to M(b-a)
fundamental theorem of calc
derivaative is the opposite of integration. if g(x) = integral f(t) and everything is continuous then g’(x) = f(x)
ODEs
ordinary diff eq - only have one independent variable x and dependent variable y
homogenous ODE
all terms involve dependent variable or one of its derivatives
Separable diff eq
first order diff eq that can be expressed as a function of y and a function of x. dy/dx = f(x)g(y)
separable diff eq solving
separate and integrate individally
first order linear
in the form of dy/dx + P(x)y = Q(x)
first order linear solving
find I(x) = e^int(P(x)), then d/dx(I(x)y = I(x)Q(x)
second order homogeneous with constant coefficients
ay’’ + by’ +cy = 0 so the functions a ,b, c are all constant.
second order homogeneous with constant coefficients solving
take y = e^rx and substitute into it. Solve quadratic for r, depending on what r is the solutions for y are different
r has 2 solutions
y = Ae^r1x + Be^r2x
r has one solution
y = Ae^rx + Bxe^rx
r = alpha +- beta i
y = e^alphax (Acos(betax) + Bsin(betax))
secondary non homogeneous with linear coefficients solving
solve for yc as normal by y=e^rx substitution.
find ypi using a general substitution, and sub into diff eq to find constants.
ygeneral = yc + ypi
improper integral type one
is one of the limits of the integral goes off to infinity, we can express this limit as t. Do the integral and take the limit as t approaches infinity, then see if it converges to a number or it fucks off
improper integral type 2
if there is a discontinuity at b, and otherwise function is continuous from a to c, then we can add integrals from a to b and from b to c.
comparison theorem
if there are two functions, one bigger than the other. If the smaller one is divergent, so is the bigger one. If the bigger one is convergent, so is the smaller one.
PArtial fractions 101
for linear, separate. for repeated, one linear one square. for irreducible, ax + b nominator. make fractions have equal denominators, add and equal to nominator of full fraction. solve
Method of cylindrical shells
integrates in little shells from line of rotation. to rotate about y we integrate in x using circumference (spix) X height (f) x with (dx). we can rotate about another line x=X by making the circumference 2pi(X-x). Likewise for rotating around x, we can rotate about y = Y, integrate in dy and all ts. height is also afected
formula for arc length
integral of sqrt(1+dy/dx^2