$\dfrac{1}{1+a^{n-m}}+\dfrac{1}{1+a^{m-n}}=?$
0
1/2
1
am + n
Explanation:
$\dfrac{1}{1+a^{n-m}}+\dfrac{1}{1+a^{m-n}}=\dfrac{1}{\left(1+\dfrac{a^{n}}{a^{m}}\right)}+\dfrac{1}{\left(1+\dfrac{a^{m}}{a^{n}}\right)}$
=$\dfrac{a^{m}}{\left(a^{m}+a^{n}\right)}+\dfrac{a^{n}}{\left(a^{m}+a^{n}\right)}$
=$\dfrac{\left(a^{m}+a^{n}\right)}{\left(a^{m}+a^{n}\right)}$
=1
$\dfrac{1}{1+a^{n-m}}+\dfrac{1}{1+a^{m-n}}=\dfrac{1}{\left(1+\dfrac{a^{n}}{a^{m}}\right)}+\dfrac{1}{\left(1+\dfrac{a^{m}}{a^{n}}\right)}$
=$\dfrac{a^{m}}{\left(a^{m}+a^{n}\right)}+\dfrac{a^{n}}{\left(a^{m}+a^{n}\right)}$
=$\dfrac{\left(a^{m}+a^{n}\right)}{\left(a^{m}+a^{n}\right)}$
=1