Examples with solutions for Square of Difference: Using fractions

Exercise #1

(1xx)2= (\frac{1}{x}-x)^2=

Video Solution

Step-by-Step Solution

To solve this problem, we'll use the square of a binomial formula:

  • Identify a=1xa = \frac{1}{x} and b=xb = x.
  • Apply the formula (ab)2=a22ab+b2(a - b)^2 = a^2 - 2ab + b^2.
  • Simplify each component and obtain the final expression.

Let's work through the steps:

Step 1: Identify the components:
a=1x a = \frac{1}{x} , b=x b = x

Step 2: Apply the formula:

(1xx)2=(1x)22×1x×x+x2(\frac{1}{x} - x)^2 = (\frac{1}{x})^2 - 2 \times \frac{1}{x} \times x + x^2

Simplifying each term:

(1x)2=1x2(\frac{1}{x})^2 = \frac{1}{x^2}

2×1x×x=2-2 \times \frac{1}{x} \times x = -2

x2=x2x^2 = x^2

Step 3: Combine and simplify:

1x22+x2\frac{1}{x^2} - 2 + x^2

To combine these into a single fraction, find a common denominator x2x^2:

1x22x2x2+x4x2=12x2+x4x2\frac{1}{x^2} - \frac{2x^2}{x^2} + \frac{x^4}{x^2} = \frac{1 - 2x^2 + x^4}{x^2}

Thus, the simplified expression is:

x42x2+1x2\frac{x^4 - 2x^2 + 1}{x^2}

Comparing to the choices provided, the correct choice is:

Choice 3: x42x2+1x2\frac{x^4 - 2x^2 + 1}{x^2}

Answer

x42x2+1x2 \frac{x^4-2x^2+1}{x^2}

Exercise #2

Consider the following relationship between x and y:

x4y+yx1=0 \frac{x}{4y}+\frac{y}{x}-1=0

Choose the short multiplication formula that represents this equation.

Video Solution

Step-by-Step Solution

To solve this problem, we'll begin by simplifying the given expression:

The equation is x4y+yx1=0 \frac{x}{4y} + \frac{y}{x} - 1 = 0 .

  • Step 1: Eliminate the fraction by obtaining a common denominator for the left side of the equation. The common denominator is 4y×x=4xy 4y \times x = 4xy .
  • Step 2: Rewrite each term with the common denominator:
    x24xy+4y24xy4y4y=0 \frac{x^2}{4xy} + \frac{4y^2}{4xy} - \frac{4y}{4y} = 0 . This becomes x2+4y24xy4xy=0 \frac{x^2 + 4y^2 - 4xy}{4xy} = 0 .
  • Step 3: Multiply through by 4xy 4xy to eliminate the denominator: x2+4y24xy=0 x^2 + 4y^2 - 4xy = 0 .
  • Step 4: Recognize this as being equivalent to the expanded form of (x2y)2=x22xy+4y2=0 (x - 2y)^2 = x^2 - 2xy + 4y^2 = 0 .
  • Step 5: Confirm that x22xy+4y2x2+4y24xy x^2 - 2xy + 4y^2 \equiv x^2 + 4y^2 - 4xy , indicating (x2y)2=0 (x - 2y)^2 = 0 .

Thus, we conclude that the equation can be rewritten using the square of a difference formula:

Therefore, the short multiplication formula for the given equation is (x2y)2=0 (x - 2y)^2 = 0 .

Answer

(x2y)2=0 (x-2y)^2=0

Exercise #3

2x24xy+2y2+(xy)2xy= \frac{\sqrt{2x^2-4xy+2y^2+(x-y)^2}}{x-y}=

Video Solution

Step-by-Step Solution

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

  • Step 1: Simplify the expression inside the square root.
  • Step 2: Utilize the algebraic identity to combine and simplify terms.
  • Step 3: Divide the result by xy x-y .

Now, let's work through each step:

Step 1: Expand (xy)2 (x-y)^2 .

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

Step 2: Simplify the square root expression:
The expression inside the square root is:
2x24xy+2y2+(xy)2 2x^2 - 4xy + 2y^2 + (x-y)^2 .
Substitute (xy)2=x22xy+y2 (x-y)^2 = x^2 - 2xy + y^2 :
2x24xy+2y2+x22xy+y2 2x^2 - 4xy + 2y^2 + x^2 - 2xy + y^2 .

This simplifies to:
3x26xy+3y2 3x^2 - 6xy + 3y^2 .

Notice that this can be rewritten using the identity (ab)2=a22ab+b2 (a-b)^2 = a^2 - 2ab + b^2 as:
3(x22xy+y2)=3(xy)2 3(x^2 - 2xy + y^2) = 3(x-y)^2 .

Step 3: Extract the square root and simplify:
3(xy)2=3×xy\sqrt{3(x-y)^2} = \sqrt{3} \times |x-y| .

Finally, divide by xy x-y :
3×xyxy=3×xyxy\frac{\sqrt{3} \times |x-y|}{x-y} = \sqrt{3} \times \frac{|x-y|}{x-y} .

Since we assume xy0 x-y \neq 0 , it simplifies to 3\sqrt{3} because xyxy=1\frac{|x-y|}{x-y} = 1 when x>yx > y, and 1-1 when x<yx < y. With the absolute value, it remains 11 in both cases.

Therefore, the solution to the problem is 3 \sqrt{3} .

Answer

3 \sqrt{3}

Exercise #4

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?

Video Solution

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.

Answer

xy=1 xy=1

Exercise #5

(1x12)2(1x13)2=94 \frac{(\frac{1}{x}-\frac{1}{2})^2}{(\frac{1}{x}-\frac{1}{3})^2}=\frac{9}{4}

Find X

Video Solution

Step-by-Step Solution

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

  • Step 1: Expand and simplify the numerator (1x12)2 (\frac{1}{x} - \frac{1}{2})^2 .
  • Step 2: Expand and simplify the denominator (1x13)2 (\frac{1}{x} - \frac{1}{3})^2 .
  • Step 3: Set up the equation as a proportion and solve for x x .

Let’s work through each step:
Step 1: Using the formula for the square of a difference, expand the numerator:

(1x12)2=(1x)22(1x)(12)+(12)2=1x21x+14(\frac{1}{x} - \frac{1}{2})^2 = \left(\frac{1}{x}\right)^2 - 2\left(\frac{1}{x}\right)\left(\frac{1}{2}\right) + \left(\frac{1}{2}\right)^2 = \frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}.

Step 2: Similarly, expand the denominator:

(1x13)2=(1x)22(1x)(13)+(13)2=1x223x+19(\frac{1}{x} - \frac{1}{3})^2 = \left(\frac{1}{x}\right)^2 - 2\left(\frac{1}{x}\right)\left(\frac{1}{3}\right) + \left(\frac{1}{3}\right)^2 = \frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}.

Step 3: Substitute these into the original equation and solve the proportion:

1x21x+141x223x+19=94\frac{\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}}{\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}} = \frac{9}{4}.

Cross-multiply to clear the fractions:

4(1x21x+14)=9(1x223x+19)4\left(\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}\right) = 9\left(\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}\right).

Simplifying both sides gives:

4(1x21x+14)=41x241x+14(\frac{1}{x^2} - \frac{1}{x} + \frac{1}{4}) = 4\frac{1}{x^2} - 4\frac{1}{x} + 1.

9(1x223x+19)=91x261x+19(\frac{1}{x^2} - \frac{2}{3x} + \frac{1}{9}) = 9\frac{1}{x^2} - 6\frac{1}{x} + 1.

Equating the expressions, we have:

41x241x+1=91x261x+14\frac{1}{x^2} - 4\frac{1}{x} + 1 = 9\frac{1}{x^2} - 6\frac{1}{x} + 1.

Subtract 1 from both sides and collect like terms:

41x+1=51x221x-4\frac{1}{x} + 1 = 5\frac{1}{x^2} - 2\frac{1}{x}.

21x51x2=0-2\frac{1}{x} - 5\frac{1}{x^2} = 0.

Factoring gives:

51x(x2)=05\frac{1}{x}(x - 2) = 0.

Therefore, the solution for x x should satisfy x2=0 x - 2 = 0 , so x=2.5 x = 2.5 .

Thus, the value of x x is 2.5\boxed{2.5}.

Answer

2.5

Exercise #6

Ax+Bx2=(2x3)2xc \frac{A}{x}+\frac{Bx}{2}=\frac{(2x-3)^2}{x}-c

Calculate the values of A, B, and C.

Video Solution

Step-by-Step Solution

To solve this problem, we'll proceed with the following steps:

  • Step 1: Expand the expression (2x3)2(2x-3)^2 on the right-hand side.
  • Step 2: Simplify the resulting expression by dividing by xx.
  • Step 3: Compare the terms on both sides of the equation to deduce the coefficients AA, BB, and CC.

Now, let us work through these steps:

Step 1: Expand the expression (2x3)2(2x-3)^2.

(2x3)2=4x212x+9 (2x - 3)^2 = 4x^2 - 12x + 9

Step 2: Substitute back into the equation and simplify by dividing by xx:

Ax+Bx2=4x212x+9xC \frac{A}{x} + \frac{Bx}{2} = \frac{4x^2 - 12x + 9}{x} - C

This simplifies to:

4x12+9xC 4x - 12 + \frac{9}{x} - C

Step 3: To find AA, BB, and CC, compare coefficients of similar terms:

  • Constant term (no xx): Equate 12-12 with C-C to get C=12C = 12 (note: should consider sign reversal).
  • Coefficient of xx: Compare B2\frac{B}{2} to 4. Giving B=8B = 8.
  • Coefficient of 1x\frac{1}{x}: Compare AA to 9, giving A=9A = 9.

Therefore, the solution to the problem is that the values are A = 9, B = 8, C = -12 \textbf{A = 9, B = 8, C = -12} .

Answer

A=9,B=8,C=12 A=9,B=8,C=-12