Square of a Difference

Square of a Difference

How to solve the square of a difference problems: formula, examples, and their solutions.

Formula

(a - b)^2 = a^2 - 2ab + b^2

(a - b)2 = (a - b)(a - b).

By using the FOIL method,
(a - b)(a - b) = a2 - 2ab + b2.

So (a - b)2 = a2 - 2ab + b2.

See the brown (-) signs.
The (-) sign in (a - b)2
makes the middle term (-): -2ab.

It's the difference between
this formula and (a + b)2 formula.

Example 1

Find the given product. (x - 7)^2

Put x, (-), 7 into the formula.

Example 2

Find the given product. (3r - 2s)^2

Put 3r, (-), 2s into the formula.