Q&A Given the sequence series \{a_n\} satisfies a_1=1 , a_2=\dfrac{2}{3} and \dfrac{1}{a_{n+1}} +\dfrac{1}{a_{n-1}}=\dfrac{2}{a_n} (n=2,3,\dots) , find the general term of a_n

Q&A If a sequence has a first term of a_1=10 , and a common difference d=5 , Write the formula that describes this sequence. Use the formula of the arithmetic sequence.