Several problems should be paid attention to in solving practical problems by listing equations: (1) the key to solving problems is to find (), and then list equations to form equations; (2) the way to solve unknowns In general, there are two kinds of methods: direct method and () method; (3) pay attention to the unit before and after the same unknown number (), the unit on both sides of each equation (), the unit of answer and question (); (4) when solving practical problems, pay special attention to (), not only to check whether the solutions are suitable for (), but also to check whether these solutions are consistent with ()

Several problems should be paid attention to in solving practical problems by listing equations: (1) the key to solving problems is to find (), and then list equations to form equations; (2) the way to solve unknowns In general, there are two kinds of methods: direct method and () method; (3) pay attention to the unit before and after the same unknown number (), the unit on both sides of each equation (), the unit of answer and question (); (4) when solving practical problems, pay special attention to (), not only to check whether the solutions are suitable for (), but also to check whether these solutions are consistent with ()

(1) The key to solve the problem is to find the equivalent relation, and then list the equations to form the equations;
(2) In general, there are two ways to deal with unknowns: direct way and indirect way;
(3) Note that the units of the same unknown should be (Unified), the units on both sides of each equation should be (same), and the answer should be (consistent) with the question unit;
(4) In solving practical problems, we should pay special attention to (check), not only to check whether the solutions are suitable for (each equation) in the original equations, but also to check whether these solutions conform to the (meaning) of the practical problems

On multiple choice questions of unknown number equation
The following four equations are given
(1) ax2+c=0(a≠0)
(2) ax2+bx=0(a≠0)
(3) ax2=0(a≠0)
(4) ax2+bx+c=0(a≠0)
The equation where there must be real roots is

(1) ax2+c=0(a≠0)
X ^ 2 = - C / a if C > 0, a > 0 has no real root
(2) ax2+bx=0(a≠0)
Therefore, it may have no real root
(3) ax2=0(a≠0)
If the solution of the equation is x = 0, then it must be an equation with real roots
(4) ax2+bx+c=0(a≠0)
Same as 2
So choose 3

1. An equation is an equation with unknowns. 2. An equation with an equal sign and a letter is called an equation. Who is right and who is wrong

It's all wrong
An equation is an equation with unknowns
"An equation is an equation with unknowns" is not an equation. For example, 2x is not an equation
The formula with equal sign and letter is called equation. For example, s = AB is a rectangle area formula