Answer :

Let's solve the expression step-by-step:

Given expression:
[tex]$\frac{m+b}{m-b} + \frac{m-b}{m+b} - \frac{m^2+b^2}{m^2-b^2}$[/tex]

1. Simplify each fraction:

- First, let’s rewrite the third term:
[tex]\[ \frac{m^2+b^2}{m^2-b^2} \][/tex]
Notice that the denominator [tex]\( m^2 - b^2 \)[/tex] can be factored as [tex]\( (m - b)(m + b) \)[/tex].

- Therefore, the expression becomes:
[tex]\[ \frac{m^2 + b^2}{(m - b)(m + b)} \][/tex]

2. Substitute the factored form back into the main expression:
[tex]\[ \frac{m+b}{m-b} + \frac{m-b}{m+b} - \frac{m^2+b^2}{(m - b)(m + b)} \][/tex]

3. Combine all the terms over a common denominator:

- The common denominator for the first two terms is [tex]\( (m-b)(m+b) \)[/tex].
- Combining them all over the common denominator gives us:
[tex]\[ \frac{(m+b)(m+b) + (m-b)(m-b) - (m^2+b^2)}{(m-b)(m+b)} \][/tex]

4. Expand the numerators of the first two fractions:

- Expanding [tex]\( (m+b)(m+b) \)[/tex]:
[tex]\[ (m+b)^2 = m^2 + 2mb + b^2 \][/tex]

- Expanding [tex]\( (m-b)(m-b) \)[/tex]:
[tex]\[ (m-b)^2 = m^2 - 2mb + b^2 \][/tex]

- Now the expression becomes:
[tex]\[ \frac{(m^2 + 2mb + b^2) + (m^2 - 2mb + b^2) - (m^2 + b^2)}{(m-b)(m+b)} \][/tex]

5. Combine like terms in the numerator:

- Summing the terms in the numerator:
[tex]\[ (m^2 + 2mb + b^2) + (m^2 - 2mb + b^2) - (m^2 + b^2) \\ = m^2 + 2mb + b^2 + m^2 - 2mb + b^2 - m^2 - b^2 \][/tex]

- Simplifying:
[tex]\[ = (m^2 + m^2 - m^2) + (2mb - 2mb) + (b^2 + b^2 - b^2) \\ = m^2 - m^2 - b^2 = -(m^2 + b^2) \][/tex]

6. Thus, the simplified form of the numerator is:
[tex]\[ -(m^2 + b^2) \][/tex]

- So, the overall expression is now:
[tex]\[ \frac{-(m^2 + b^2)}{(m-b)(m+b)} \][/tex]

7. This can be further simplified to:
[tex]\[ -\frac{m^2 + b^2}{m^2 - b^2} \][/tex]

So, the fully simplified expression is:
[tex]\[ -\frac{m^2 + b^2}{m^2 - b^2} \][/tex]

And in terms of the given result:
[tex]\[ (-b^2 - m^2)/(b^2 - m^2) \][/tex]

Thus, our final simplified answer is:
[tex]\[ -\frac{b^2 + m^2}{b^2 - m^2} \][/tex]

Hope this helps!