There is a parent parabola, which is stretch horizontally by a factor of 2 and vertically by a factor of 6, and shifted 7 units to the left then 8 units downwards. What is the equation of the resultant function? (翻译:有一个抛物线的母函数(最简单形式),被横向拉长2倍,纵向拉长6倍,向上平移8个单位,向左平移7个单位。由以上步骤得到的新函数图形的解析式是?)