Question | Answer |
ordinary differential equations | equations involving a function and its derivatives |
order | the order of the highest derivative |
general solution | y=mt+b since we don't know the values for m and b |
particular solution | a solution with a specific value for c, from an initial value problem |
interval of existence | a set of t-values for which the solution x(t) is defined |
existence and uniqueness theorem | if f(t,x) and its derivative are continuous near x0 and t0 then the IVP has one and only one solution |
autonomous | if the RHSde has no explicit t's |
homogeneous | if q(t)=0 in an ode |
linear ode formula | dx/dt=p(t)*x+ q(t) |
integrating factor | used to write the LHS as the derivative of the product of itself and the dependent variable x |
law of cooling | dx/dt= a(x(t)-b) and soln: x(t)=b+(x0-b)*e^(-at) |
exponential decay | dx/dt=-r*x and soln: x(t)=x0*e^(-rt) |
exponential growth | dx/dt=-r*x and soln: x(t)=x0*e^(rt) |
general form for nonhomogeneous ode | x=xh+xp assuming p is constant |
critical point/equilibrium | in an autonomous ode set dx/dt=0 to find this |
3 types of equilibriaugh | sink, source, shunt |
sink | if f is decreasing through xe, also if f'(xe)<0 |
source | if f is increasing through xe, also if f'(xe)>0 |
shunt | if f has a local min or max at xe |
nonhyperbolic equilibrium | if f'(xe)=0 |
hyperbolic equilibrium | if f'(xe)does not =0, this is easier to determine behavior from |
linearization | way of studying solutions of nonlinear x'=f(x) near a hyperbolic equilibrium xe |
separation of variables | can be used for all autonomous and some nonautonomous odes if x'=f(t,x) can be separated to f(t,x)=g(t)*h(x) |