complete solution 2025/2026
Linear Differential Equation - correct answer ✔The dependent var and its derivatives appear in additive
combos of their first power
Separable DE - correct answer ✔Separable can be written as: P(y) dy/dx = q(x) and separated as P(y)dy
= q(x)dx
1st order linear DE - correct answer ✔standard form: y' + p(x)y = q(x)
Integrating factor method:
-find I(x) = e^int(p(x)dx)
-solve: (I(x)y)' = I(x)q(x)
Mixing problem - correct answer ✔C(t) = A(t)/V(t)
dV/dt = r1-r2
dA/dt = C1r1-C2r2
dA/dt + r2A/V = C1r1 (1st order linear)
Exact Equations - correct answer ✔M(x,y) +N(x,y) dy/dx = 0 (2 distinct funcs, =0 and "+")
Ix = M, Iy = N, if exact, My = Nx
I(x,y) = C
integrate Mdx, to get I, have +h(y) instead of +C, Iy = N to find h(y)
Bernoulli DE - correct answer ✔Form: y' +p(x)y = q(x)y^n (linear with y^n)
Solve: (1) divide by y^n, use v=y^1-n, v' = (1-n)(y^-n)y'