Algebra Examples

$r^{2} - 4 r + 4$

Step 1

Rewrite $4$ as $2^{2}$ .

$r^{2} - 4 r + 2^{2}$

Step 2

Check that the middle term is two times the product of the numbers being squared in the first term and third term.

$4 r = 2 \cdot r \cdot 2$

Step 3

Rewrite the polynomial.

$r^{2} - 2 \cdot r \cdot 2 + 2^{2}$

Step 4

Factor using the perfect square trinomial rule $a^{2} - 2 a b + b^{2} = {(a - b)}^{2}$ , where $a = r$ and $b = 2$ .

${(r - 2)}^{2}$