Identify Type of Equation: Identify the type of differential equation. This is a second-order linear homogeneous differential equation with constant coefficients.
Guess Solution Form: Guess a solution of the form y=erx.We'll substitute this into the differential equation to find the value of r.
Substitute into Equation: Substitute y=erx into the equation.dx2d2y+y=r2⋅erx+erx=0
Factor Out: Factor out erx. erx∗(r2+1)=0
Set Equal to Zero: Set the expression in parentheses equal to zero. r2+1=0
Solve for r: Solve for r.r2=−1r=±i
Write General Solution: Write the general solution.y=C1⋅eix+C2⋅e−ixBut eix and e−ix can be expressed using Euler's formula as cos(x) and sin(x).
Express Using Trig Functions: Express the solution using trigonometric functions.y=C1⋅cos(x)+C2⋅sin(x)
More problems from Evaluate integers raised to rational exponents