$\"\"$

(a)

The equation is $\"\"$ .

Consider $\"\"$ .

The expression $\"\"$ is undefined for $\"\"$ .

Now consider $\"\"$ .

The value of the expression $\"\"$ at $\"\"$ is $\"\"$ .

The equation $\"\"$ is true except at $\"\"$

So $\"\"$ when $\"\"$ .

$\"\"$

(b)

The equation is $\"\"$ .

Consider $\"\"$ .

Rewrite the equation.

$\"\"$

Therefore $\"\"$ is true.

$\"\"$

(a) $\"\"$ when $\"\"$ .

(b) $\"\"$ is true.