<span><span><span><span>x2</span>+<span>y2</span></span><span><span>−6</span>x</span></span><span><span>−8</span>y</span></span>=<span><span>−21</span>+<span>0
</span></span><span><span><span><span>x2</span>+<span>y2</span></span><span><span>−6</span>x</span></span><span><span>−8</span>y</span></span>=<span>−<span>21
</span></span><span><span>(<span>x<span>−3</span></span>)</span>2</span><span>−<span>9
</span></span><span><span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span><span>−9</span></span>+<span>y2</span></span><span><span>−8</span>y</span></span>=<span>−<span>21
</span></span><span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span>+<span>y2</span></span><span><span>−8</span>y</span></span>=<span><span>−21</span>+<span>9
</span></span><span><span>(<span>y<span>−4</span></span>)</span>2</span><span>−<span>16
</span></span><span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span>+<span><span>(<span>y<span>−4</span></span>)</span>2</span></span><span>−16</span></span>=<span><span>−21</span>+<span>9
</span></span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span><span><span>(<span>y<span>−4</span></span>)</span>2</span></span>=<span><span><span>−21</span>+9</span>+<span>16
</span></span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span>+<span><span>(<span>y<span>−4</span></span>)</span>2</span></span>=<span><span>−12</span>+<span>16
</span></span><span><span><span>(<span>x<span>−3</span></span>)</span>2</span>+<span><span>(<span>y<span>−4</span></span>)</span>2</span></span>=<span>4</span>
