1, substitution method
Solve the following equation:
The solution process of replacement method is:
And then play it?
Substitute into one of the equations:
So its solution is:
2. Drawing method
Drawing is to draw two equations on the map, and the intersection of the two lines is the solution. Solve the following equation:
First, draw them on the map:
What is green?
Red is
The intersection of two lines is their solution:
3. Exclusion method
Solve the following equation by elimination method:
Subtract the left and right sides of the equal sign of two equations respectively: the upper formula-the lower formula,
And then play it?
Substitute into one of the equations:
Draw:
The basic idea of solving binary linear equations
Eliminate ideas
"Elimination" is the basic idea of solving binary linear equations. The so-called "elimination" is to reduce the number of unknowns, so that the multivariate equation can eventually be transformed into a univariate multivariate equation and then the unknowns can be solved. This solution, that is, the solution in which the number of unknowns in the equation decreases from more to less, is called elimination solution.
Elimination methods are generally divided into: substitution elimination method, referred to as substitution method; Addition, subtraction and elimination method, abbreviation: addition and subtraction; Sequential exclusion method; Integral replacement method
elimination by substitution
The unknown number of one equation in the equation group is expressed by an algebraic expression containing another unknown number, which is substituted into another equation, and an unknown number is eliminated to obtain a linear equation with one variable, and finally the solution of the equation group is obtained. This method of solving equations is called substitution elimination method.
Addition and subtraction
When the coefficients of the unknowns of two equations in an equation are equal or opposite, the unknowns are eliminated by adding or subtracting the two sides of the two equations, so that the binary linear equation is transformed into a unitary linear equation, and finally the solution of the equations is obtained. This method of solving equations is called addition, subtraction and elimination.
Alternative method
Method of substitution is often used to solve some complex problems, that is, polynomials with complex structures. If we regard some parts as a whole and replace them with new letters, we can simplify and clarify complex problems. This method can play a unique role in reducing the number of polynomial terms and the complexity of polynomial structure.