$\"\"$

The function is $\"\"$

Compare it to $\"\"$

$\"\"$

Since $\"\"$ , then the graph of parabola open upward.

So the function has minimum value.

$\"\"$

Find the vertex of above quadratic function $\"\"$

$\"\"$ coordinate of vertex is axis of symmetry $\"\"$

$\"\"$

The minimum value is $\"\"$

$\"\"$

Replace $\"\"$ with $\"\"$ .

$\"\"$

$\"\"$ $\"\"$

The minimum value of the function is $\"\"$ .