The degree is the power to which the highest derivative is raised to if the DE. Is a polynomial in it's derivative. That is ay' + by'' + cy''' and so on. But the moment you have a trigonometric, transcendental or logarithmic term of (any of the derivative of the dependent variable y) in the DE. Then the degree is undefined. Eg y' + cos (y'') has undefined degree, but y' + y'' has a degree of 1.
you are so wrong. to determine the order of a differential equation the equation should be in polynomial form as far as derivatives are concerned . otherwise order is not define. you 1st equation is trigonometric not polynomial then order is not define. same in 4th one.
Thanks for your contribution, but that is incorrect, order does not depend on whether the DE is a polynomial in its derivative or not, but rather the degree. Kindly take note. Thank you.
according to the rule, whenever we have the trig, exponential or logarithmic functions of the dependent variable in this case y, then the de has no order, but in this case we have the trig functions of the independent variable, x.