Solving the Square Root Equation: Find (x, y) for √x - √y = √(√61 - 6) and xy = 9

Radical Equations with Product Constraints

Solve the following system of equations:

{xy=616xy=9 \begin{cases} \sqrt{x}-\sqrt{y}=\sqrt{\sqrt{61}-6} \\ xy=9 \end{cases}

❤️ Continue Your Math Journey!

We have hundreds of course questions with personalized recommendations + Account 100% premium

Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:13 Let's solve this system of equations together.
00:16 First, let's square the first equation. Great job!
00:20 We can use the special multiplication formulas to square it. Isn't that neat?
00:30 Now, take the square root of the second equation. You're doing well!
00:43 Substitute the second equation into the first. Keep going!
00:55 Let's simplify it whenever you can. Nice work!
01:01 Here, we find the expression for X. You're almost there!
01:08 Now, plug X back into the second equation to find Y. Keep it up!
01:13 Open those parentheses carefully, multiplying each term. You've got this!
01:22 Arrange the equation so it equals zero on one side. Nearly done!
01:26 Find the two solutions for Y. Excellent!
01:39 These are the solutions for Y. Good work!
01:46 Insert the solutions for Y back into the expression for X to find X. Keep going!
02:03 These are the possible solutions for X and Y. Well done!
02:07 And that is the solution to our problem! Excellent job!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

Solve the following system of equations:

{xy=616xy=9 \begin{cases} \sqrt{x}-\sqrt{y}=\sqrt{\sqrt{61}-6} \\ xy=9 \end{cases}

2

Step-by-step solution

To solve the problem, we will proceed with the following steps:

  • Step 1: Calculate the value of 616\sqrt{\sqrt{61}-6}.
  • Step 2: Express y\sqrt{y} in terms of x\sqrt{x} using the first equation.
  • Step 3: Form a single-variable equation to solve for x\sqrt{x}.
  • Step 4: Back-substitute to find y\sqrt{y}.
  • Step 5: Use squaring to find xx and yy as needed.

Step 1: Compute 616\sqrt{\sqrt{61}-6}.

Calculate 616617.81\sqrt{61}-6 \to \sqrt{61} \approx 7.81 . Therefore, 6161.81\sqrt{61}-6 \approx 1.81. Thus 616=1.81\sqrt{\sqrt{61}-6} = \sqrt{1.81}. For efficacy, we solve further using variables.

Step 2: Using the equation xy=616\sqrt{x} - \sqrt{y} = \sqrt{\sqrt{61}-6}, let x=a\sqrt{x} = a and y=b\sqrt{y} = b with ab=ca-b = c and referred c as calculated.

Step 3: With ab=9=3 ab = \sqrt{9} = 3 (as xy=9xy = 9 hence xy\sqrt{x}\sqrt{y}), we substitute b=3ab = \frac{3}{a}.

Thus, a3a=616a - \frac{3}{a} = \sqrt{\sqrt{61} - 6}. Rearrange into: a2a6163=0 a^2 - a\sqrt{\sqrt{61} - 6} - 3 = 0 as a quadratic equation in aa.

Solving yields solutions for aa, use quadratic formula, or completing squares.

Solving, get solutions, a=6122.5a = \frac{\sqrt{61}}{2} - 2.5 and 612+2.5\frac{\sqrt{61}}{2} + 2.5

Backward solve bb by substituting values back.

Thus, for each aa, solve for xx or yy square them and check.

The solution is:

x=6122.5 x=\frac{\sqrt{61}}{2}-2.5 , y=612+2.5 y=\frac{\sqrt{61}}{2}+2.5 or x=612+2.5 x=\frac{\sqrt{61}}{2}+2.5 , y=6122.5 y=\frac{\sqrt{61}}{2}-2.5

Final solution:

x=6122.5 x=\frac{\sqrt{61}}{2}-2.5

y=612+2.5 y=\frac{\sqrt{61}}{2}+2.5

or

x=612+2.5 x=\frac{\sqrt{61}}{2}+2.5

y=6122.5 y=\frac{\sqrt{61}}{2}-2.5

3

Final Answer

x=6122.5 x=\frac{\sqrt{61}}{2}-2.5

y=612+2.5 y=\frac{\sqrt{61}}{2}+2.5

or

x=612+2.5 x=\frac{\sqrt{61}}{2}+2.5

y=6122.5 y=\frac{\sqrt{61}}{2}-2.5

Key Points to Remember

Essential concepts to master this topic
  • System Setup: Use substitution x=a \sqrt{x} = a and y=b \sqrt{y} = b to simplify
  • Key Relationship: From xy=9 xy = 9 , we get ab=3 ab = 3 , so b=3a b = \frac{3}{a}
  • Verification: Check both xy=9 xy = 9 and xy=616 \sqrt{x} - \sqrt{y} = \sqrt{\sqrt{61} - 6}

Common Mistakes

Avoid these frequent errors
  • Solving equations separately instead of as a system
    Don't solve xy=616 \sqrt{x} - \sqrt{y} = \sqrt{\sqrt{61} - 6} alone = infinite solutions! This ignores the constraint xy=9 xy = 9 which limits solutions to specific values. Always use both equations together by substitution to find the unique solution pair.

Practice Quiz

Test your knowledge with interactive questions

\( (4b-3)(4b-3) \)

Rewrite the above expression as an exponential summation expression:

FAQ

Everything you need to know about this question

Why do we substitute x=a \sqrt{x} = a and y=b \sqrt{y} = b ?

+

This substitution simplifies the radical equation into a more manageable form. Instead of working with nested radicals, we get ab=616 a - b = \sqrt{\sqrt{61} - 6} and ab=3 ab = 3 , which is easier to solve!

How do I get from xy=9 xy = 9 to ab=3 ab = 3 ?

+

Since a=x a = \sqrt{x} and b=y b = \sqrt{y} , we have ab=xy=xy=9=3 ab = \sqrt{x} \cdot \sqrt{y} = \sqrt{xy} = \sqrt{9} = 3 . This is a key property of radicals!

Why does this system have two solution pairs?

+

When we solve the quadratic equation for a a , we get two values. Each value of a a gives a corresponding b b value, creating two valid (x,y) pairs that satisfy both original equations.

What if I get negative values under the square root?

+

Always check that your final answers make mathematical sense! Since we're dealing with x \sqrt{x} and y \sqrt{y} , both x x and y y must be non-negative for real solutions.

How do I verify my final answer is correct?

+

Substitute your (x,y) (x,y) values back into both original equations:

  • Check that xy=9 xy = 9
  • Check that xy=616 \sqrt{x} - \sqrt{y} = \sqrt{\sqrt{61} - 6}

If both are satisfied, your solution is correct!

🌟 Unlock Your Math Potential

Get unlimited access to all 18 Equations and Systems of Quadratic Equations questions, detailed video solutions, and personalized progress tracking.

📹

Unlimited Video Solutions

Step-by-step explanations for every problem

📊

Progress Analytics

Track your mastery across all topics

🚫

Ad-Free Learning

Focus on math without distractions

No credit card required • Cancel anytime

More Questions

Click on any question to see the complete solution with step-by-step explanations