model of a quadric

例句：

1. 1. The quadric equation is a mathematical model that describes the shape of a cube.
   四次方程是描述立方体形状的数学模型。
2. 2. In physics, the quadric surface is a type of surface that can be described by the equation z = ax^4 + bx^3 + cx^2 + dx + e.
   在物理学中，四次曲面是一种表面类型，可以通过方程z=ax^4+bx^3+cx^2+dx+e来描述。
3. 3. The quadric function is used in geometry to describe the shape of a curved surface.
   四次函数在几何学中用于描述曲面的形状。