Imekuwa zaidi ya miaka 10 tangu nilipojifunza hii katika shule ya upili. Sasa nadhani hatimaye ninaelewa formula ya derivative baada ya mtu huyu kuhutubia kwa dakika 20.####[['formula', 'Mathematical_Related_Concept', 'POS'], ['derivative', 'Mathematical_Related_Concept', 'POS'], ['NULL', 'Instructor', 'POS']]