Найдите производную функции [latex]y=(2x+5)^{- frac{1}{2} } [/latex]

One day Hodzha lost his donkey . While looking for it he was also rejoicing When the people saw him they asked each other Why he  was so happy  Then they asked hodzha What  the reason was of being so happy and if he   hadnt   lost his  donkey . Hodzha told them that he was  happy because he  hadnt been  riding the donkey when it had got  lost. and If he had been, he  would be lost then , too!"