Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Differential Equations

Question:

Solve : y''2 + y' - 6y = 0

Options:

e-3x

e3x

e-6x

e6x

Correct Answer:

e-3x

Explanation:

Put d/dx = D

D2y + Dy - 6y = 0

D2 + D - 6 = 0

D2 +3D - 2D - 6 = 0

D(D+3) -2(D+3) = 0

D=-3,2

for D=-3 ⇒ d/dx=-3

dy/dx=-3y

dy/y=-3dx

ln y=-3x

y=e-3x

Similarly, solve for D=2.