Why do equations have many forms?

不同的格式有不同的意思。线性方程最明显。

For a quadratic equation ax2+bx+c = 0,

the sum of its roots = –b/a and the product of its roots = c/a.

A quadratic equation may be expressed as a product of two binomials.

(x-a)(x-b) = 0

This method is called factoring.

A monomial is an algebraic expression with only one term in it. Example: x3, 2x, y2, 3xyz etc.

A polynomial is an algebraic expression with more than one term in it. Alternatively, it can be stated as – polynomial is formed by adding/subtracting multiple monomials. Example: x3+2y2+6x+10, 3x2+2x-1, 7y-2 etc. A polynomial that contains two terms is called a binomial expression. A polynomial that contains three terms is called a trinomial expression.

(x- D) 2+ A      

(x-B1) ( x-B2)   factoring 

Ax2 + bx + C