Math Problem Statement

If x×dy/dx-y= 3 , and x= 1 when y = -2, then the relationship between x and y is ?? a) |y+3| = |x| , b)|x+3| = |y|. the right answer is a, but why does it contain absolute value?

Solution

To understand why the correct answer y+3=x|y + 3| = |x| contains absolute values, let's solve the given differential equation and apply the initial condition.

Given: xdydxy=3x \frac{dy}{dx} - y = 3

This can be rewritten as: xdydx=y+3x \frac{dy}{dx} = y + 3 dydx=y+3x\frac{dy}{dx} = \frac{y + 3}{x}

This is a first-order linear differential equation. We can solve it using an integrating factor. The general form of the first-order linear differential equation

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Absolute Value
Initial Value Problem

Formulas

Integrating factor for solving first-order linear differential equations

Theorems

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Suitable Grade Level

Advanced High School