Linear Algebra Examples

$[\begin{array}{c} 1 & 1 & \frac{1}{a^{2} + b^{2} - 2 a b} \\ 0 & 0 & - \frac{1}{a - b} \\ 0 & 0 & 1 \end{array}]$

Step 1

Rearrange terms.

$[\begin{array}{c} 1 & 1 & \frac{1}{a^{2} - 2 a b + b^{2}} \\ 0 & 0 & - \frac{1}{a - b} \\ 0 & 0 & 1 \end{array}]$

Step 2

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

$2 a b = 2 \cdot a \cdot b$

Step 3

Rewrite the polynomial.

$[\begin{array}{c} 1 & 1 & \frac{1}{a^{2} - 2 \cdot a \cdot b + b^{2}} \\ 0 & 0 & - \frac{1}{a - b} \\ 0 & 0 & 1 \end{array}]$

Step 4

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

$[\begin{array}{c} 1 & 1 & \frac{1}{{(a - b)}^{2}} \\ 0 & 0 & - \frac{1}{a - b} \\ 0 & 0 & 1 \end{array}]$