A first-order equation involves dy ÷ dx and separating variables rearranges dy ÷ dx = f(x)g(y) into dy ÷ g(y) = f(x) dx, so this Year 13 sheet starts from the first derivative. The key also records y = Ceᵏˣ as a standard solution form.
Key Takeaways
A first-order equation involves dy ÷ dx (Q1).
Separation turns dy ÷ dx = f(x)g(y) into dy ÷ g(y) = f(x) dx (Q2).
The key records y = Ceᵏˣ as a solution form.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.A first-order differential equation involves
(a) dy ÷ dx(b) d²y ÷ dx²(c) ∫ y dx(d) y²
2.To separate the variables in dy ÷ dx = f(x)g(y), you rearrange the equation to
(a) dy ÷ g(y) = f(x) dx(b) dy = f(x) dx(c) g(y) dy = f(x) + dx(d) nothing can be done
3.The general solution of a first-order differential equation contains
(a) one arbitrary constant(b) two arbitrary constants(c) no constants(d) three constants
4.A particular solution is found by using
(a) an initial condition(b) the general solution(c) another differential equation(d) the integral sign
5.The solution of dy ÷ dx = ky (exponential growth) is
(a) y = Ceᵏˣ(b) y = Ckx(c) y = kC(d) y = k eˣ
6.An equation of the form d²y ÷ dx² + a dy ÷ dx + by = 0 is