I have this question 1. Solve the following DE’s, by inspection.

y’= -sin x

I Know that y=cos x and y'= -sin x. Then is y=cos x the answer? What does it mean when solve by inspection???

Printable View

- Nov 11th 2012, 10:39 PMtjsdndnjsSolving differential equations by inspection!
I have this question 1. Solve the following DE’s, by inspection.

y’= -sin x

I Know that y=cos x and y'= -sin x. Then is y=cos x the answer? What does it mean when solve by inspection??? - Nov 11th 2012, 10:49 PMMarkFLRe: Solving differential equations by inspection!
Solving by inspection involves exactly what you did (well, almost, you forgot the constant of integration)...you know that:

and so we must have:

- Nov 11th 2012, 10:55 PMtjsdndnjsRe: Solving differential equations by inspection!
Oh thanks for the reply!

Then let's say for y'' = 3 and I did. y'=3x+c

y= (3/2)x^2 +C

Then is y= (3/2)x^2 + C answer for y"=3?

Thank you. - Nov 11th 2012, 11:06 PMMarkFLRe: Solving differential equations by inspection!
No, for the second example, you should observe that:

hence: