Hàm số y = x sinx + cosx có vi phân là:
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Lời giải:
Báo sai\(% MathType!MTEF!2!1!+- % feaahqart1ev3aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn % hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr % 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9 % vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x % fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaaeaaaaaaaaa8 % qacaWGKbGaamyEaiabg2da9maabmaabaGaamiEaiGacohacaGGPbGa % aiOBaiaadIhacqGHRaWkciGGJbGaai4BaiaacohacaWG4baacaGLOa % GaayzkaaWaaWbaaSqabeaakiadacUHYaIOaaGaaeizaiaadIhacqGH % 9aqpdaqadaqaaiGacohacaGGPbGaaiOBaiaadIhacqGHRaWkcaWG4b % Gaci4yaiaac+gacaGGZbGaamiEaiabgkHiTiGacohacaGGPbGaaiOB % aiaadIhaaiaawIcacaGLPaaacaqGKbGaamiEaiabg2da98aadaqada % qaa8qacaWG4bGaci4yaiaac+gacaGGZbGaamiEaaWdaiaawIcacaGL % PaaapeGaaeizaiaadIhaaaa!6547! dy = {\left( {x\sin x + \cos x} \right)^\prime }{\rm{d}}x = \left( {\sin x + x\cos x - \sin x} \right){\rm{d}}x = \left( {x\cos x} \right){\rm{d}}x\)