The formula of square difference refers to the product of the sum of two numbers and the difference of two numbers, which is equal to the square difference of two numbers. The letters in the formula can not only represent specific algebraic expressions such as numbers, letters, monomials or polynomials.
Among the formulas of trigonometric functions, there is a group of formulas called trigonometric square difference formula. Named after the square difference formula, it is mainly used to solve triangles.
Common mistakes and preventive measures
First, common mistakes
Common mistakes in variance formula:
① It is difficult for students to jump out of the original fixed thinking, such as typical mistakes; (Error reason: analogy based on formula, and "creation" at will)
② Confusion formula;
(3) The symbol in the operation result is wrong;
④ Variant application is difficult to master.
Second, matters needing attention
On the left side of the formula is the product of two terms, one of which is exactly the same.
The result on the right is the square difference of two terms in the multiplication formula, the square of the same term MINUS the square of the inverse term.
In the formula, a and b can be specific numbers, monomials or polynomials.