Is taking a method explanation from books and papers considered plagiarism?
If you are using somebody else's words, you need to make this fact clear and explicit via quotation/block quotation; to do otherwise is clearly plagiarism, even if you are splicing together multiple different sources into some sort of Frankenparagraph.  

If you are making a complex remix of two sources, proper quotation may feel very choppy and incoherent, however, so you are probably better off paraphrasing into your own words instead.