Finding tangent equations of both lines through the point (2,-3) that are tangent to the parabola y=x^2 + x.
I found the derivative which is 2x + 1 then I'm stuck.
Any help/advice are greatly appreciated ! Thanks !
The equation of a line tangent to the parabola at (a, a^2 + a) is given by y = (2a + 1)(x - a) + a^2 + a = (2a + 1)x - a^2. This line goes through (2, -3) iff (2a + 1)*2 - a^2 = 3. So you need to solve the quadratic equation a^2 - 4a + 1 = 0 for a and plug the answers into the equation for the line.