Solve System: (x²+y²)/(x-y)² = 3 and (x-y)² = 1 for Product xy

System of Equations with Algebraic Substitution

x2+y2(xy)2=3,(xy)2=1 \frac{x^2+y^2}{(x-y)^2}=3,(x-y)^2=1

What is the product of x and y?

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Step-by-step video solution

Watch the teacher solve the problem with clear explanations
00:14 Let's find the value of X Y.
00:20 First, we'll substitute the known values from the data.
00:34 Next, we'll use the second formula provided.
00:38 Now, apply the multiplication rules to simplify.
00:44 Rearrange the equation into a simpler form.
00:52 Substitute the value we already found and keep solving.
01:00 Focus on isolating the variable X Y.
01:13 And that's how we find the solution to this question!

Step-by-step written solution

Follow each step carefully to understand the complete solution
1

Understand the problem

x2+y2(xy)2=3,(xy)2=1 \frac{x^2+y^2}{(x-y)^2}=3,(x-y)^2=1

What is the product of x and y?

2

Step-by-step solution

To solve this problem, we'll follow these steps:

  • Step 1: Substitute the given value of (xy)2(x-y)^2 into the first equation.
  • Step 2: Use the identity for a square of a difference to find a relationship between x2+y2x^2 + y^2 and xyxy.
  • Step 3: Solve for the product xyxy.

Now, let's work through each step:

Step 1: We start with the provided equation:

x2+y2(xy)2=3\frac{x^2 + y^2}{(x-y)^2} = 3

Given that (xy)2=1(x-y)^2 = 1, we substitute:

x2+y21=3\frac{x^2 + y^2}{1} = 3

which simplifies to:

x2+y2=3x^2 + y^2 = 3

Step 2: We know from the identity of a square of a difference:

(xy)2=x22xy+y2(x-y)^2 = x^2 - 2xy + y^2

Given (xy)2=1(x-y)^2 = 1, we can write:

x22xy+y2=1x^2 - 2xy + y^2 = 1

Step 3: We set up a system of equations:

x2+y2=3x^2 + y^2 = 3 (Equation 1)

x22xy+y2=1x^2 - 2xy + y^2 = 1 (Equation 2)

Subtract Equation 2 from Equation 1:

(x2+y2)(x22xy+y2)=31(x^2 + y^2) - (x^2 - 2xy + y^2) = 3 - 1

Simplifying the left side gives 2xy2xy:

2xy=22xy = 2

Divide both sides by 2:

xy=1xy = 1

Therefore, the product of xx and yy is xy=1xy = 1.

3

Final Answer

xy=1 xy=1

Key Points to Remember

Essential concepts to master this topic
  • Substitution Rule: Replace known values to simplify complex equations first
  • Identity Technique: Use (xy)2=x22xy+y2(x-y)^2 = x^2 - 2xy + y^2 to connect variables
  • System Check: Verify xy=1xy = 1 by substituting back into both original equations ✓

Common Mistakes

Avoid these frequent errors
  • Trying to solve for individual x and y values first
    Don't attempt to find x = 2, y = 1/2 separately before finding xy! This creates unnecessary complexity with multiple solutions. The problem only asks for the product xy, so work directly toward that using algebraic identities and substitution.

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 don't I need to find the actual values of x and y?

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The question only asks for the product xy, not the individual values! By using algebraic identities, you can find xy = 1 without solving for x and y separately, which is much more efficient.

How do I know which algebraic identity to use?

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Look for patterns in your equations. When you see (xy)2(x-y)^2, think of the expansion: x22xy+y2x^2 - 2xy + y^2. This connects to x2+y2x^2 + y^2 through the 2xy term.

What if I get a different answer when I try to solve for x and y individually?

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There are actually multiple (x,y) pairs that satisfy this system! For example, (x,y) could be (2, 1/2) or (-2, -1/2). But notice that in both cases, xy=1xy = 1.

How can I verify my answer is correct?

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Substitute xy = 1 back into your work. Check that x2+y2=3x^2 + y^2 = 3 and x22xy+y2=1x^2 - 2xy + y^2 = 1 are consistent when xy=1xy = 1.

Is there a faster way to see this relationship?

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Yes! Notice that subtracting the second equation from the first gives: (x2+y2)(x22xy+y2)=2xy(x^2 + y^2) - (x^2 - 2xy + y^2) = 2xy. So 2xy=31=22xy = 3 - 1 = 2, which means xy=1xy = 1!

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