Solve Rational Expression: (2x+1)²/(x+2) + (x+2)²/(2x+1) = 4.5x

Rational Equations with Complex Algebraic Manipulation

Solve the following equation:

(2x+1)2x+2+(x+2)22x+1=4.5x \frac{(2x+1)^2}{x+2}+\frac{(x+2)^2}{2x+1}=4.5x

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Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following equation:

(2x+1)2x+2+(x+2)22x+1=4.5x \frac{(2x+1)^2}{x+2}+\frac{(x+2)^2}{2x+1}=4.5x

2

Step-by-step solution

In order to solve the equation, start by removing the denominators.

To do this, we'll multiply the denominators:

(2x+1)2(2x+1)+(x+2)2(x+2)=4.5x(2x+1)(x+2) (2x+1)^2\cdot(2x+1)+(x+2)^2\cdot(x+2)=4.5x(2x+1)(x+2)

Open the parentheses on the left side, making use of the distributive property:

(4x2+4x+1)(2x+1)+(x2+4x+4)(x+2)=4.5x(2x+1)(x+2) (4x^2+4x+1)\cdot(2x+1)+(x^2+4x+4)\cdot(x+2)=4.5x(2x+1)(x+2)

Continue to open the parentheses on the right side of the equation:

(4x2+4x+1)(2x+1)+(x2+4x+4)(x+2)=4.5x(2x2+5x+2) (4x^2+4x+1)\cdot(2x+1)+(x^2+4x+4)\cdot(x+2)=4.5x(2x^2+5x+2)

Simplify further:

(4x2+4x+1)(2x+1)+(x2+4x+4)(x+2)=9x3+22.5x+9x (4x^2+4x+1)\cdot(2x+1)+(x^2+4x+4)\cdot(x+2)=9x^3+22.5x+9x

Go back and simplify the parentheses on the left side of the equation:

8x3+8x2+2x+4x2+4x+1+x3+4x2+4x+2x2+8x+8=9x3+22.5x+9x 8x^3+8x^2+2x+4x^2+4x+1+x^3+4x^2+4x+2x^2+8x+8=9x^3+22.5x+9x

Combine like terms:

9x3+18x2+18x+9=9x3+22.5x+9x 9x^3+18x^2+18x+9=9x^3+22.5x+9x

Notice that all terms can be divided by 9 as shown below:

x3+2x2+2x+1=x3+2.5x+x x^3+2x^2+2x+1=x^3+2.5x+x

Move all numbers to one side:

x3x3+2x22.5x2+2xx+9=0 x^3-x^3+2x^2-2.5x^2+2x-x+9=0

We obtain the following:

0.5x2x1=0 0.5x^2-x-1=0

In order to remove the one-half coefficient, multiply the entire equation by 2

x22x2=0 x^2-2x-2=0

Apply the square root formula, as shown below-

2±122 \frac{2±\sqrt{12}}{2}

Apply the properties of square roots in order to simplify the square root of 12:

2±232 \frac{2±2\sqrt{3}}{2} Divide both the numerator and denominator by 2 as follows:

1±3 1±\sqrt{3}

3

Final Answer

x=1±3 x=1±\sqrt{3}

Key Points to Remember

Essential concepts to master this topic
  • Clear Denominators: Multiply entire equation by common denominator LCD
  • Technique: Expand (2x+1)2=4x2+4x+1 (2x+1)^2 = 4x^2+4x+1 before multiplying
  • Check: Substitute x=1+3 x=1+\sqrt{3} back into original equation ✓

Common Mistakes

Avoid these frequent errors
  • Expanding terms incorrectly when clearing denominators
    Don't multiply just the numerators by the opposite denominators = missing terms and wrong equation! This creates algebraic errors that compound throughout the solution. Always multiply the entire fraction by the missing factor from the LCD.

Practice Quiz

Test your knowledge with interactive questions

Determine if the simplification shown below is correct:

\( \frac{7}{7\cdot8}=8 \)

FAQ

Everything you need to know about this question

Why do we multiply by (2x+1)(x+2) instead of just clearing one denominator?

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We need a common denominator to clear both fractions at once. Using (2x+1)(x+2) (2x+1)(x+2) as our LCD eliminates both denominators simultaneously, keeping the equation balanced.

How do I expand (2x+1)² correctly?

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Use the formula (a+b)2=a2+2ab+b2 (a+b)^2 = a^2 + 2ab + b^2 . So (2x+1)2=(2x)2+2(2x)(1)+12=4x2+4x+1 (2x+1)^2 = (2x)^2 + 2(2x)(1) + 1^2 = 4x^2 + 4x + 1 .

Why does the cubic term cancel out?

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After expanding and simplifying both sides, we get 9x3 9x^3 on both sides of the equation. When we subtract, the cubic terms eliminate each other, leaving us with a quadratic equation.

How do I simplify √12 to 2√3?

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Factor out perfect squares: 12=4×3=4×3=23 \sqrt{12} = \sqrt{4 \times 3} = \sqrt{4} \times \sqrt{3} = 2\sqrt{3} . Always look for perfect square factors to simplify radicals.

Can I use a calculator to check my answer?

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Yes! Substitute x=1+3 x = 1 + \sqrt{3} (approximately 2.732) back into the original equation. Both sides should equal the same value when calculated.

What if I get a different quadratic after clearing denominators?

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Double-check your algebraic expansion and like term combination. The most common errors happen when multiplying out the polynomials or combining terms with the same degree.

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