What’s on the Difference of Squares poster
The rule, 4 worked examples, and the mistake everyone makes.
- A difference of two squares always factors into a sum times a difference.
- a² − b² = (a + b)(a − b)
- x² − 16 = (x+4)(x−4)
- 9x² − 25 = (3x+5)(3x−5)
- x⁴ − 81 = (x²+9)(x²−9)
- x² + 16 = does not factor
- Common mistake: x² + 16 = (x+4)(x+4) → x² + 16 does not factor over the reals
Difference of squares factors. Sum of squares does not — not with real numbers.
Questions about the Difference of Squares poster
- What’s on the Difference of Squares poster?
- The rule, 4 worked examples, and the mistake everyone makes. A difference of two squares always factors into a sum times a difference.; a² − b² = (a + b)(a − b); x² − 16 = (x+4)(x−4); 9x² − 25 = (3x+5)(3x−5); x⁴ − 81 = (x²+9)(x²−9); x² + 16 = does not factor; Common mistake: x² + 16 = (x+4)(x+4) → x² + 16 does not factor over the reals. Difference of squares factors. Sum of squares does not — not with real numbers.
- Who is the Difference of Squares poster for?
- Difference of Squares is filed under 9th Grade (ages 14–15), so it matches what that year asks a child to remember. It is equally useful to an older student revisiting math, and to the parent or teacher answering the question at the kitchen table.
- When should you use the Difference of Squares poster?
- Check: two terms, both perfect squares, separated by a minus. All three, or it is not this. A wall chart earns its place by being glanceable from where the work is happening, so Difference of Squares belongs on the wall where that math work actually happens, within glancing distance, rather than filed away.
- What other posters go with Difference of Squares?
- Absolute Value Equations, Arithmetic Sequences and Exponential Functions sit alongside Difference of Squares in the 9th Grade set. Printed together they make a wall rather than a single sheet, which is how a reference set actually gets used.Absolute Value EquationsArithmetic SequencesExponential Functions
- Is the Difference of Squares poster free to download and print?
- Yes. Difference of Squares downloads as a free PDF with no account, no email and no watermark, like everything else in the 9th Grade set. Print as many copies as you like for a home, a classroom, a library or a tutoring group; reselling the file is the only thing the licence rules out.Read the licence
- What size does the Difference of Squares poster print at?
- Difference of Squares is a vector PDF laid out for US Letter, and prints on A4 with Fit to page — the same file, no separate download. Because every mark on it is drawn rather than photographed, it stays sharp enlarged to A3, A2 or A1 at a copy shop. Colour carries emphasis only, so a greyscale print of Difference of Squares loses nothing.Printing guide
Related posters
Charts that sit alongside Difference of Squares on the same wall.
Browse every 9th Grade poster, or start from the full catalogue.