Best practice in product development is a dynamic target. Not only are new practices being developed and refined but the differences in organisations demand the tailored application of these practices. There are eight basic companies, all projects and at all times. But the company philosoph knowledge, skills and assets change; and these changes cause changes in the types of product innovations and the activities in product development Successful companies recognise that product development is an important strategic issue that demands constant attention. There is a need to evaluate the product development performance and the product development success rate
∑ ∞ = − 0 0 )( n n n xxa = a0 + )(1 0 − xxa 2 2 0 −+ xxa )( +\+ n n xxa )( − 0 +\ 这样的函数项级数称为幂级数。幂级数的部分和函数 Sn(x)是一个n −1 次多项式。 为了方便，我们通常取 0 x = 0, 也就是讨论 ∑ ∞ n=0 n n xa = a0 + 1 xa 2 2 + xa +\+ n n xa +\， 然后对所得的结果做一个平移 x = 0 − xt ，就可以平行推广到x0 ≠ 0的情 况
