- #1
Karol
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Homework Statement
Find dy of ##~xy^2+x^2y=4##
Homework Equations
Differential of a product:
$$d(uv)=u\cdot dv+v\cdot du$$
The Attempt at a Solution
$$2xy~dy+y^2~dx+x^2~dy+2xy~dx=0$$
$$x(2y+x)dy=-(y+2x)dx$$
You miss a y on the RHS.Karol said:Homework Statement
Find dy of ##~xy^2+x^2y=4##
Homework Equations
Differential of a product:
$$d(uv)=u\cdot dv+v\cdot du$$
The Attempt at a Solution
$$2xy~dy+y^2~dx+x^2~dy+2xy~dx=0$$
$$x(2y+x)dy=-(y+2x)dx$$
What type of meaning are you considering? You can see it as ##\frac{1}{y} dy ##.Karol said:$$x(2y+x)dy=-y(y+2x)dx$$
$$\frac{dy}{y}=-\frac{y+2x}{2y+x}~\frac{dx}{x}$$
Is there a meaning for ##~\frac{dy}{y}~##?
$$2xy\frac{dy}{dx}+y^2+x^2\frac{dy}{dx}+2xy=0$$WWGD said:Then differentiate the whole expression as a function of x, using the chain rule on y=y(x).
Good, but no need to split the dy/dx. Leave it as a single unit and solve for it.Karol said:$$2xy\frac{dy}{dx}+y^2+x^2\frac{dy}{dx}+2xy=0$$
$$dy=-\frac{y^2+2xy}{x^2+2xy}~dx$$
$$\frac{dy}{dx}=-\frac{y^2+2xy}{x^2+2xy}$$WWGD said:Good, but no need to split the dy/dx. Leave it as a single unit and solve for it.
Sorry, then do split into dy and dx parts.I am not clear, just what is your goal here, to find y?Karol said:$$\frac{dy}{dx}=-\frac{y^2+2xy}{x^2+2xy}$$
What i can do, and i can't even that, is to integrate, but it's not the point and the book didn't teach it yet.
What else can i do with a derivative which involves y?
I need dy, that is what i was asked, and any dy=f(x)dx
I need to express, find, what is y=y(x)
I was asked to find dyWWGD said:just what is your goal here, to find y?
My apologies then, do separate dy and dx and solve for dy.Karol said:I was asked to find dy
" undeveloped"? How so? What is the book's answer?Karol said:Now i see that the book's answer is like mine, leaving y undevelopped
WWGD said:" undeveloped"? How so? What is the book's answer?
I see, thanks.Karol said:
The differential of a y mixed with x refers to the change in y with respect to a change in x. In other words, it is the rate of change of y in relation to x.
The differential of a y mixed with x is important because it helps us understand the relationship between two variables and how they affect each other. It is also used in many mathematical and scientific equations to analyze and predict changes in a system.
The differential of a y mixed with x is calculated using the derivative function, which involves finding the slope of the tangent line to a curve at a specific point. This can be done using various methods, such as the power rule, product rule, and chain rule.
Yes, the differential of a y mixed with x can be negative. This means that the change in y is decreasing as the change in x increases, indicating an inverse relationship between the two variables.
The differential of a y mixed with x is used in various fields, including physics, engineering, economics, and biology. It can help us understand and predict changes in systems and make informed decisions based on the relationship between variables.