Comparative exclusion-exclusion of dissidents This method should exclude obviously wrong or unreasonable alternative answers one by one according to the requirements of the topic on the basis of reading the meaning of the topic, and finally leave only the correct answer. If the option is completely positive or negative, it can be excluded by giving a counterexample; If there are contradictory or mutually exclusive options between the options, one of the two options may be correct, and of course both options may be wrong, but they can never be both correct.
Extreme thinking method-The common methods of extreme thinking embodied in universal physics include extreme thinking method and infinitesimal method. When the physical quantities involved in the topic change monotonously with the conditions, the available limit method is to push a physical quantity to the limit, that is, extreme value or minimum, extreme left or extreme right, and make scientific reasoning and analysis accordingly, so as to give a judgment or derive a general conclusion.
The infinitesimal method is to decompose the physical process or research object into many tiny ones.
"infinitesimal", only need to use the necessary mathematical methods or physical ideas to deal with these "infinitesimal", the problem can be solved.
For general mathematical problems, the problem can be specialized in the process of solving problems, and the principle that the problem does not hold in special circumstances and does not hold in general circumstances can be used to achieve the purpose of removing the false and retaining the true. ? Example: the three vertices of △abc are on the ellipse 4x2+5y2=6, in which two points A and B are symmetrical about the origin O. Let the slope of the straight line ac be k 1 and the slope of the straight line bc be k2, then the value of k 1k2 is? A -5/4b. -4/5c.4/5d.2√5/5？ Analysis: Because the value of k 1k2 is required, we can know from the stem that the value of k 1k2 is a fixed value. There are no specific positions of A, B and C in the question, because it is a multiple-choice question, so there is no need to solve it. Through simple drawing, we can get the most easily calculated value. We might as well make A and B two vertices on the long axis of the ellipse and C one vertex on the short axis of the ellipse, so we can directly confirm the intersection point and simplify the problem, so we choose B.