Square of Difference Practice Problems with Solutions

Master the (a-b)² formula with step-by-step practice problems. Learn to expand square of difference expressions using algebraic shortcuts and verify solutions.

📚Master Square of Difference Formula Through Practice
  • Apply the (X-Y)² = X² - 2XY + Y² formula to algebraic expressions
  • Expand binomial squares with negative terms step-by-step
  • Solve square of difference problems with both variables and numbers
  • Identify when to use the difference square formula versus full expansion
  • Practice with mixed expressions combining algebraic and numerical terms
  • Verify expanded forms by working backwards to original expressions

Understanding Square of Difference

Complete explanation with examples

Difference of Squares Formula

The difference of squares formula is another key algebraic shortcut that simplifies expressions involving two squared terms subtracted from each other. It is written as:

(XY)2=X22XY+Y2(X - Y)^2=X^2 - 2XY + Y^2
This formula skips the need for full expansion and directly factors the expression. It works for both numerical and algebraic expressions, making it versatile in solving equations and simplifying terms. That is, when we encounter two numbers with a minus sign between them, that is, the difference and they will be in parentheses and raised as a squared expression, we can use this formula.

For (xy)2(x - y)^2 the full expansion would be:
(xy)2=(xy)(xy)=xx+x(y)yxy(y)=x22xy+y2(x - y)^2=(x-y)(x−y)=x⋅x+x⋅(-y)-y⋅x−y⋅(-y)=x^2-2xy+y^2

Visual breakdown of abbreviated multiplication formulas: (a+b)² = a² + 2ab + b² and (a−b)² = a² − 2ab + b², with color-coded area models representing the expansion of binomials

Example:

(a4)2=(a - 4)^2=
a×a+a×(4)+(4)×a+(4)×(4)=a\times a+a\times (-4)+ (-4)\times a + (-4) \times (-4) =
a2+2(4a)+(4)2=a^2+2(-4a)+ (-4)^2 =
a28a+16a^2-8a+16

Detailed explanation

Practice Square of Difference

Test your knowledge with 15 quizzes

\( (x-2)^2+(x-3)^2= \)

Examples with solutions for Square of Difference

Step-by-step solutions included
Exercise #1

Declares the given expression as a sum

(7b3x)2 (7b-3x)^2

Step-by-Step Solution

To solve for (7b3x)2(7b - 3x)^2 as a sum, we'll follow these steps:

  • Step 1: Identify the given expression and apply the formula for the square of a difference:
    (ab)2=a22ab+b2(a - b)^2 = a^2 - 2ab + b^2 where a=7ba = 7b and b=3xb = 3x.
  • Step 2: Expand each term:
    • a2=(7b)2=49b2a^2 = (7b)^2 = 49b^2
    • 2ab=2×7b×3x=42bx-2ab = -2 \times 7b \times 3x = -42bx
    • b2=(3x)2=9x2b^2 = (3x)^2 = 9x^2
  • Step 3: Combine all terms to form the sum:
    (7b3x)2=49b242bx+9x2 (7b - 3x)^2 = 49b^2 - 42bx + 9x^2 .

Therefore, the solution to the problem is (7b3x)2=49b242bx+9x2(7b - 3x)^2 = 49b^2 - 42bx + 9x^2.

Hence, the correct answer choice is: 49b242bx+9x2 49b^2 - 42bx + 9x^2

Answer:

49b242bx+9x2 49b^2-42bx+9x^2

Video Solution
Exercise #2

(xx2)2= (x-x^2)^2=

Step-by-Step Solution

To solve the expression (xx2)2(x-x^2)^2, we will use the square of a binomial formula (ab)2=a22ab+b2(a-b)^2 = a^2 - 2ab + b^2.

Let's identify aa and bb in our expression:

  • Here, a=xa = x and b=x2b = x^2.

Applying the formula:

(xx2)2=(x)22(x)(x2)+(x2)2(x - x^2)^2 = (x)^2 - 2(x)(x^2) + (x^2)^2

Calculating each part, we get:

  • (x)2=x2(x)^2 = x^2
  • 2(x)(x2)=2x3-2(x)(x^2) = -2x^3
  • (x2)2=x4(x^2)^2 = x^4

Combining these results, the expression simplifies to:

x42x3+x2x^4 - 2x^3 + x^2

Therefore, the expanded form of (xx2)2(x-x^2)^2 is x42x3+x2\boxed{x^4 - 2x^3 + x^2}.

Answer:

x42x3+x2 x^4-2x^3+x^2

Video Solution
Exercise #3

Choose the expression that has the same value as the following:

(x7)2 (x-7)^2

Step-by-Step Solution

To solve the problem, we need to expand the expression (x7)2(x-7)^2 using the formula for the square of a difference.

The formula for the square of a difference is (ab)2=a22ab+b2(a-b)^2 = a^2 - 2ab + b^2.

Let's apply this formula to our expression (x7)2(x-7)^2:

  • Identify a=xa = x and b=7b = 7.
  • Substitute these values into the formula: (x7)2=x22(x)(7)+72(x-7)^2 = x^2 - 2(x)(7) + 7^2.
  • Calculate each term:
    • x2x^2 remains as x2x^2.
    • 2(x)(7)=14x-2(x)(7) = -14x.
    • 72=497^2 = 49.

So, expanding the expression, we get x214x+49x^2 - 14x + 49.

Thus, the expression that has the same value as (x7)2(x-7)^2 is x214x+49x^2 - 14x + 49.

Answer:

x214x+49 x^2-14x+49

Video Solution
Exercise #4

(a4)(a4)=? (a-4)(a-4)=\text{?}

Step-by-Step Solution

To solve the problem, we will expand the expression (a4)(a4)(a-4)(a-4) using the square of a difference formula.

This formula states: (xy)2=x22xy+y2(x-y)^2 = x^2 - 2xy + y^2.
In our case, x=ax = a and y=4y = 4, so we apply the formula:

  • First term: x2=a2x^2 = a^2
  • Second term: 2xy=2a4=8a-2xy = -2 \cdot a \cdot 4 = -8a
  • Third term: y2=42=16y^2 = 4^2 = 16

Putting it all together, the expression becomes:
a28a+16a^2 - 8a + 16.

After matching this result with the given choices, we find it corresponds to choice 4.

Therefore, the solution to the problem is a28a+16\mathbf{a^2 - 8a + 16}.

Answer:

a28a+16 a^2-8a+16

Video Solution
Exercise #5

Rewrite the following expression as an addition and as a multiplication:

(3xy)2 (3x-y)^2

Step-by-Step Solution

To solve this problem, let's start by identifying the parts of the binomial:

  • The expression (3xy)2(3x-y)^2 represents a binomial squared.
  • We recognize it has the form (ab)2(a-b)^2 where a=3xa = 3x and b=yb = y.
  • Using the formula for the square of a difference: (ab)2=a22ab+b2(a-b)^2 = a^2 - 2ab + b^2, we find the expanded form.

Let's apply the formula:

Step 1: Expand (3xy)2(3x-y)^2 using the formula:
(3xy)2=(3x)22(3x)(y)+y2(3x-y)^2 = (3x)^2 - 2(3x)(y) + y^2

Step 2: Calculate each part:
(3x)2=9x2(3x)^2 = 9x^2
2(3x)(y)=6xy-2(3x)(y) = -6xy
y2y^2 stays as y2y^2

Step 3: Combine these results to get the addition form:
9x26xy+y29x^2 - 6xy + y^2

The expression in multiplication form, as provided, is just repeating the factors:
(3xy)(3xy)(3x-y)(3x-y)

Therefore, the expression rewritten as addition is 9x26xy+y29x^2 - 6xy + y^2 and as multiplication (3xy)(3xy)(3x-y)(3x-y).

Answer:

9x26xy+y2 9x^2-6xy+y^2

(3xy)(3xy) (3x-y)(3x-y)

Video Solution

Frequently Asked Questions

What is the square of difference formula?

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The square of difference formula is (X-Y)² = X² - 2XY + Y². This algebraic shortcut helps expand expressions where two terms with a minus sign between them are squared together, avoiding the need for full multiplication.

How do you expand (a-b)² step by step?

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To expand (a-b)²: 1) Square the first term: a², 2) Multiply both terms by 2 with a negative sign: -2ab, 3) Square the second term: b². The result is a² - 2ab + b².

What's the difference between (a+b)² and (a-b)² formulas?

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The key difference is in the middle term sign. For (a+b)² = a² + 2ab + b², the middle term is positive. For (a-b)² = a² - 2ab + b², the middle term is negative due to the minus sign in the original expression.

Can you use the square of difference formula with numbers?

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Yes, the formula works with both algebraic variables and numbers. For example, (x-7)² = x² - 14x + 49, where 7 is treated as the second term Y in the formula X² - 2XY + Y².

Why is the middle term negative in (a-b)²?

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The middle term becomes negative because when you multiply (a-b)(a-b), you get ax(-b) + (-b)xa = -2ab. The negative signs from both multiplications create the -2XY term in the final expansion.

What are common mistakes when expanding square of difference?

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Common mistakes include: • Forgetting the negative sign in the middle term • Writing +2ab instead of -2ab • Not squaring the second term correctly • Confusing it with difference of squares (a²-b²) formula

How do you verify your square of difference expansion is correct?

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You can verify by: 1) Substituting specific values for variables in both original and expanded forms, 2) Using the distributive property to multiply (a-b)(a-b) manually, 3) Factoring your expanded result back to the original form.

When should you use the square of difference formula vs full expansion?

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Use the formula when you see a binomial expression with a minus sign squared, like (x-5)². It's faster than full expansion and reduces calculation errors. Use full expansion only when the formula doesn't apply or for verification purposes.

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