addition of polynomial

例句：

1. 1. The function f(x) = x^2 + 3x + 2 is a polynomial of degree 3.
   函数f(x)=x^2+3x+2是二次数的。
2. 2. In the polynomial addition, we add together all the coefficients and constants.
   在多项式加法中，我们把所有的系数和常数相加。
3. 3. The polynomial addition can be used to solve systems of linear equations.
   多项式加法可以用来解线性方程组。