Find the equation of the straight line that is tangent to the curve 2x^2 - 5x - 3 =0 when x = 3.

First differentiate 2x² - 5x - 3 to get 4x -5. At x = 3, the gradient of the tangent must be 7, and we know it goes through (3, 0) Plug the values into y = mx + c to get the equation of the line, which is y = 7x -21