Calculus Examples

Solve the Differential Equation 1/x(dy)/(dx)-1/(1+x^2)y=x^3
Step 1
Rewrite the differential equation as .
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Step 1.1
Rewrite the equation as .
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Step 1.1.1
Reorder terms.
Step 1.1.2
Reorder terms.
Step 1.2
Factor out of .
Step 1.3
Reorder and .
Step 1.4
Multiply each term in by .
Step 1.5
Combine and .
Step 1.6
Combine and .
Step 1.7
Combine and .
Step 1.8
Combine and .
Step 1.9
Multiply by by adding the exponents.
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Step 1.9.1
Multiply by .
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Step 1.9.1.1
Raise to the power of .
Step 1.9.1.2
Use the power rule to combine exponents.
Step 1.9.2
Add and .
Step 1.10
Cancel the common factor of .
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Step 1.10.1
Cancel the common factor.
Step 1.10.2
Divide by .
Step 1.11
Factor out of .
Step 1.12
Reorder and .
Step 2
The integrating factor is defined by the formula , where .
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Step 2.1
Set up the integration.
Step 2.2
Integrate .
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Step 2.2.1
Since is constant with respect to , move out of the integral.
Step 2.2.2
Let . Then , so . Rewrite using and .
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Step 2.2.2.1
Let . Find .
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Step 2.2.2.1.1
Differentiate .
Step 2.2.2.1.2
By the Sum Rule, the derivative of with respect to is .
Step 2.2.2.1.3
Differentiate using the Power Rule which states that is where .
Step 2.2.2.1.4
Since is constant with respect to , the derivative of with respect to is .
Step 2.2.2.1.5
Add and .
Step 2.2.2.2
Rewrite the problem using and .
Step 2.2.3
Simplify.
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Step 2.2.3.1
Multiply by .
Step 2.2.3.2
Move to the left of .
Step 2.2.4
Since is constant with respect to , move out of the integral.
Step 2.2.5
The integral of with respect to is .
Step 2.2.6
Simplify.
Step 2.2.7
Replace all occurrences of with .
Step 2.3
Remove the constant of integration.
Step 2.4
Use the logarithmic power rule.
Step 2.5
Exponentiation and log are inverse functions.
Step 2.6
Rewrite the expression using the negative exponent rule .
Step 3
Multiply each term by the integrating factor .
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Step 3.1
Multiply each term by .
Step 3.2
Simplify each term.
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Step 3.2.1
Combine and .
Step 3.2.2
Rewrite using the commutative property of multiplication.
Step 3.2.3
Combine and .
Step 3.2.4
Multiply .
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Step 3.2.4.1
Multiply by .
Step 3.2.4.2
Multiply by by adding the exponents.
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Step 3.2.4.2.1
Multiply by .
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Step 3.2.4.2.1.1
Raise to the power of .
Step 3.2.4.2.1.2
Use the power rule to combine exponents.
Step 3.2.4.2.2
Write as a fraction with a common denominator.
Step 3.2.4.2.3
Combine the numerators over the common denominator.
Step 3.2.4.2.4
Add and .
Step 3.3
Combine and .
Step 4
Rewrite the left side as a result of differentiating a product.
Step 5
Set up an integral on each side.
Step 6
Integrate the left side.
Step 7
Integrate the right side.
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Step 7.1
Apply the rule to rewrite the exponentiation as a radical.
Step 7.2
Let , where . Then . Note that since , is positive.
Step 7.3
Simplify terms.
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Step 7.3.1
Simplify .
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Step 7.3.1.1
Apply pythagorean identity.
Step 7.3.1.2
Multiply the exponents in .
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Step 7.3.1.2.1
Apply the power rule and multiply exponents, .
Step 7.3.1.2.2
Multiply by .
Step 7.3.1.3
Pull terms out from under the radical, assuming positive real numbers.
Step 7.3.2
Cancel the common factor of .
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Step 7.3.2.1
Factor out of .
Step 7.3.2.2
Cancel the common factor.
Step 7.3.2.3
Rewrite the expression.
Step 7.4
Raise to the power of .
Step 7.5
Simplify with factoring out.
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Step 7.5.1
Factor out of .
Step 7.5.2
Rewrite as exponentiation.
Step 7.6
Using the Pythagorean Identity, rewrite as .
Step 7.7
Simplify.
Step 7.8
Simplify terms.
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Step 7.8.1
Apply the distributive property.
Step 7.8.2
Simplify each term.
Step 7.9
Split the single integral into multiple integrals.
Step 7.10
The integral of with respect to is .
Step 7.11
Since is constant with respect to , move out of the integral.
Step 7.12
The integral of with respect to is .
Step 7.13
Since is constant with respect to , move out of the integral.
Step 7.14
The integral of with respect to is .
Step 7.15
Simplify.
Step 7.16
Replace all occurrences of with .
Step 8
Solve for .
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Step 8.1
Simplify the left side.
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Step 8.1.1
Combine and .
Step 8.2
Simplify the right side.
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Step 8.2.1
Simplify each term.
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Step 8.2.1.1
Simplify each term.
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Step 8.2.1.1.1
Draw a triangle in the plane with vertices , , and the origin. Then is the angle between the positive x-axis and the ray beginning at the origin and passing through . Therefore, is .
Step 8.2.1.1.2
The functions tangent and arctangent are inverses.
Step 8.2.1.2
Simplify each term.
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Step 8.2.1.2.1
Draw a triangle in the plane with vertices , , and the origin. Then is the angle between the positive x-axis and the ray beginning at the origin and passing through . Therefore, is .
Step 8.2.1.2.2
The functions tangent and arctangent are inverses.
Step 8.2.1.3
Multiply .
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Step 8.2.1.3.1
Reorder and .
Step 8.2.1.3.2
Simplify by moving inside the logarithm.
Step 8.2.1.4
Remove the absolute value in because exponentiations with even powers are always positive.
Step 8.2.1.5
Simplify each term.
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Step 8.2.1.5.1
Draw a triangle in the plane with vertices , , and the origin. Then is the angle between the positive x-axis and the ray beginning at the origin and passing through . Therefore, is .
Step 8.2.1.5.2
The functions tangent and arctangent are inverses.
Step 8.3
Move all the terms containing a logarithm to the left side of the equation.
Step 8.4
Rewrite the equation as .
Step 8.5
Subtract from both sides of the equation.
Step 8.6
Divide each term in by and simplify.
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Step 8.6.1
Divide each term in by .
Step 8.6.2
Simplify the left side.
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Step 8.6.2.1
Dividing two negative values results in a positive value.
Step 8.6.2.2
Divide by .
Step 8.6.3
Simplify the right side.
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Step 8.6.3.1
Simplify each term.
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Step 8.6.3.1.1
Dividing two negative values results in a positive value.
Step 8.6.3.1.2
Divide by .
Step 8.6.3.1.3
Move the negative one from the denominator of .
Step 8.6.3.1.4
Rewrite as .
Step 8.6.3.1.5
Dividing two negative values results in a positive value.
Step 8.6.3.1.6
Divide by .
Step 8.6.3.1.7
Dividing two negative values results in a positive value.
Step 8.6.3.1.8
Divide by .
Step 8.7
Multiply both sides by .
Step 8.8
Simplify.
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Step 8.8.1
Simplify the left side.
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Step 8.8.1.1
Cancel the common factor of .
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Step 8.8.1.1.1
Cancel the common factor.
Step 8.8.1.1.2
Rewrite the expression.
Step 8.8.2
Simplify the right side.
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Step 8.8.2.1
Simplify .
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Step 8.8.2.1.1
Apply the distributive property.
Step 8.8.2.1.2
Simplify the expression.
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Step 8.8.2.1.2.1
Reorder and .
Step 8.8.2.1.2.2
Move .
Step 8.8.2.1.2.3
Reorder and .