What you'll practice

A difference of squares is a two-term expression where both terms are perfect squares separated by a minus sign, like $x^2 - 49$. It factors in one move: $a^2 - b^2 = (a+b)(a-b)$. These questions train you to spot the pattern fast — including coefficients ($9x^2 - 16$) and two-variable forms ($4x^2 - 25y^2$).

Worked example

Common mistakes

• Trying to factor a SUM of squares: $x^2 + 49$ does not factor over the reals — the pattern needs a minus.
• Forgetting the coefficient is squared too: $9x^2 - 16 = (3x+4)(3x-4)$, not $(9x+4)(x-4)$.
• Stopping too early: $x^4 - 16 = (x^2+4)(x^2-4)$, and $x^2 - 4$ factors again into $(x+2)(x-2)$.

Try a few

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FAQ

What is the difference of squares formula?

a² − b² = (a + b)(a − b). Any two perfect squares separated by a minus sign factor this way: x² − 49 = (x + 7)(x − 7).

How do you recognize a difference of squares?

Two terms, both perfect squares, separated by a minus sign. If any of those three checks fails, the pattern doesn't apply.

Does a sum of squares factor?

Not over the real numbers. x² + 49 stays as it is — only the difference pattern factors into (a+b)(a−b).

Is Cramzoo free?

Cramzoo is free to start — every unit opens with free skills and no account is needed. This particular skill is part of Premium ($6/month or $30/year), which unlocks every skill plus the parent progress dashboard.

How is this different from IXL?

No punishing score. A wrong answer gives you a step-by-step explanation, not a number that drops — and every question is double-checked for accuracy before it reaches you.

Related Algebra 2 skills

• Factor quadratic trinomials
• Factor out the GCF