Find an equation for the line tangent to the curve at the point defined by the given value of t. Also, find the value of d2y dx2 at this point. x = 2t3 + 4, y = t6, t = −1 Write the equation of the tangent line. y = What is the value of d2y dx2 at this point? d2y dx2 = (Type an integer or a simplified fraction. )