Math Chapter Wise Limit, Continuity And Differentiability Of Function Of Two Variables And Partial Differentiation English MCQ UP PCS (Pre) 2000 Q.If 3 3 1 x y u tan x y − + = − then u u x y ∂ ∂ + ∂ ∂ is equal to: Asin 2u Bcos 2u Ctan 2u Dcot 2u Show answer Correct answer: sin 2u