Which of these is a solution of dy/dx + y = 0?

Differential Equations · Question 29 of 67

Question 29

MediumOriginal question

Which of these is a solution of $\frac{dy}{dx} + y = 0$ ?

y = e^{x}

Correct answerYour answer

y = x e^{- x}

Correct answerYour answer

y = - e^{x}

Correct answerYour answer

y = 5 e^{- x}

Correct answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer D

Correct answer: D

Try $y = 5 e^{- x}$ : $y' = - 5 e^{- x}$ .
Substituting makes both sides equal for every $x$ ; each of the others leaves something over.

Ten questions from Differential Equations, at your own pace.

Ten questions from Differential Equations, at your own pace.