Math Problem Statement

sqrt(3x)(1+/(x+y))=2 sqrt(7y)(1-1/(x+y))=4sqrt(2)

Solution

You have the system of equations:

  1. 3x(1+1x+y)=2\sqrt{3x}(1 + \frac{1}{x + y}) = 2
  2. 7y(11x+y)=42\sqrt{7y}(1 - \frac{1}{x + y}) = 4\sqrt{2}

Let's solve this step by step.

Step 1: Introduce substitutions

First, let's introduce new variables to simplify the equations:

Let:

  • u=x+yu = x + y

Then, the equations become:

  1. 3x(1+1u)=2\sqrt{3x} \left( 1 + \frac{1}{u} \right) = 2
  2. 7y(11u)=42\sqrt{7y} \left( 1 - \frac{1}{u} \right) = 4\sqrt{2}

Step 2: Solve the first equation for 3x\sqrt{3x}

From the first equation:

3x(1+1u)=2\sqrt{3x} \left( 1 + \frac{1}{u} \right) = 2

Isolate 3x\sqrt{3x}:

3x=21+1u=2uu+1\sqrt{3x} = \frac{2}{1 + \frac{1}{u}} = \frac{2u}{u + 1}

Step 3: Solve the second equation for 7y\sqrt{7y}

From the second equation:

7y(11u)=42\sqrt{7y} \left( 1 - \frac{1}{u} \right) = 4\sqrt{2}

Isolate 7y\sqrt{7y}:

7y=4211u=42uu1\sqrt{7y} = \frac{4\sqrt{2}}{1 - \frac{1}{u}} = \frac{4\sqrt{2}u}{u - 1}

Step 4: Combine the two equations

Now we have:

  1. 3x=2uu+1\sqrt{3x} = \frac{2u}{u + 1}
  2. 7y=42uu1\sqrt{7y} = \frac{4\sqrt{2}u}{u - 1}

Next, square both sides of each equation to express xx and yy in terms of uu.

  • From the first equation:

3x=(2uu+1)23x = \left( \frac{2u}{u + 1} \right)^2

x=4u23(u+1)2x = \frac{4u^2}{3(u + 1)^2}

  • From the second equation:

7y=(42uu1)27y = \left( \frac{4\sqrt{2}u}{u - 1} \right)^2

y=32u27(u1)2y = \frac{32u^2}{7(u - 1)^2}

Step 5: Express x+yx + y

We know that:

x+y=ux + y = u

Substitute the expressions for xx and yy:

4u23(u+1)2+32u27(u1)2=u\frac{4u^2}{3(u + 1)^2} + \frac{32u^2}{7(u - 1)^2} = u

Now we need to solve this equation for uu. This will involve combining the terms on the left-hand side by finding a common denominator, simplifying, and solving for uu.

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations
Square Roots
Substitution

Formulas

sqrt{3x}(1 + 1/(x + y)) = 2
sqrt{7y}(1 - 1/(x + y)) = 4sqrt{2}
x = (4u^2) / (3(u + 1)^2)
y = (32u^2) / (7(u - 1)^2)

Theorems

Substitution method
Solving systems of equations

Suitable Grade Level

Grades 11-12