2 marks A13. Given that = = e' and y = te", find the formula for d'y A: (1 - the-2t B: (1 - t)e- C (2t -3)e-3t D: te-2t 2 marks A14. A curve C is given by parametric equations = = 2t3 and y = 1 + 4t - +. Find the slope of the tangent to C at the point (20, 30) = (-2,-4). A: -1 B: - C: 0 D: E:1 2 marks A15. A curve C is given by parametric equations z = t? -t-6 and y = 2t. How many times does C cross the y-axis as t varies from -5 to 5? A: never B: once C: two times D: three times E: four times