DHARMSINH DESAI UNIVERSITY, NADIAD FACULTY OF TECHNOLOGY B.TECH. SEMESTER IV [EC, CH, CL, IT, IC] SUBJECT: MATHEMATICS - IV Examination : First Sessional Seat No. : ___________ Date : 04/01/2021 Day : Monday Time : 11.20 to 12.15 Max. Marks : 24 INSTRUCTIONS: 1. Figures to the right indicate maximum marks for that question. 2. The symbols used carry their usual meanings. 3. Assume suitable data, if required & mention them clearly. 4. Draw neat sketches wherever necessary. Q.2 Attempt Any Three from the following questions. [12] 2 2 2 (a) If the directional derivative of = ax y + by z + cz x at the point (1, 1, 1) has maximum magnitude 15 in the direction of the line parallel to the line 𝑥−1 𝑦−3 = −2 = 𝑧 . Find the values of a, b, c. 2 (b) Solve: 𝑥𝑒 𝑥 − 2 = 0 using Regula Falsi method correct up to three decimal places. (c) Find the angle between the surfaces 𝑥 2 + 𝑦 2 + 𝑧 2 = 9 and 𝑧 = 𝑥 2 + 𝑦 2 − 3 at the point (2, -1, 2). (d) Prove that: √1 + 𝛿 2 𝜇2 = 1 + 𝛿 2 = cosh(ℎ𝑑) 2 Q.3 (a) Prove that ∆𝑥 𝑚 − 1 ∆2 𝑥 𝑚 + 1∙3 ∆3 𝑥 𝑚 − 1∙3∙5 ∆4 𝑥 𝑚 +. . . . . . . . = (𝑥 + 1)𝑚 − (𝑥 − 1)𝑚 2 2∙4 2∙4∙6 2 2 [4] (b) Find the approximate value of the real root of the equation 2𝑥 − log10 𝑥 − 7 = 0 using [4] Newton Raphson method correct up to three decimal places. [4] ar ar a (c) For a constant vector 𝑎⃗ and position vector 𝑟⃗ prove that = − + 3 r 5 3 3 r r r OR Q.3 (𝑛−𝑥 1 ) ∆𝑦𝑛−1 2 n-𝑥 𝑛−𝑥 (a) Prove that: 𝑦𝑥 = 𝑦𝑛 − + (𝑛−𝑥 ∆ 𝑦𝑥 2 ) ∆ 𝑦𝑛−2 +. . . . . . + (−1) (b) Obtain root of the equation 𝑥 3 − 3𝑥 + 1 = 0 using direct iteration method by applying 6 iterations. 1 (c) Find ∇2 ( ), where 𝑟⃗ is position vector. 𝑟 Page 1 of 1 [4] [4] [4]