Math Chapter Wise Vector, Gradient And Curl English MCQ (GIC) PGT, 2015 Q.Which of the following identities is not correct? Agrad(ψ) = grad ψ + ψ grad φ Bdiv(a) = div a + a grad φ Cdiv(a b) = b.curl a + a curl b × Dcurl(a) = curl a + (grad) a φ × Show answer Correct answer: div(a b) = b.curl a + a curl b ×