In junior high school, we only touched the linear function and quadratic function in mathematics, but in senior high school, we added power function, exponential function, logarithmic function and so on, and these functions are often combined to form compound functions. Especially when finding the domain, range, monotonicity, parity and maximum value of a function, the basic elementary is very simple, but when they are combined to form a compound function, it will make the problem very difficult. Senior one can only find these according to the definition, which will make the problem-solving process very complicated and the amount of calculation is very large, leading to anxiety and unwillingness to do it.
Especially quadratic function, is a fucking asshole, such as: f (x) = ax 2+bx+c, a is not zero. Since B and C are known, it is simple but troublesome to judge the monotonicity on the interval according to A, first to see whether A is greater than zero or less than zero, and then to look at the relationship between the symmetry axis and the interval. But knowing A and C, it is much easier to find the monotonicity of an interval according to B. ..
There are other situations, which are actually very simple, but we think of him as complicated. For example, the maximum value of f(x)= √( x2+ 16)-x in the interval [-3,0]. To find the maximum, we must first find monotonicity. If this is a fill-in-the-blank question or multiple-choice question, it is a waste of time to find it by definition. √ (x 2+ 16) and -x are subtraction functions in the interval [-3,0], and subtraction functions are addition and subtraction functions or subtraction functions. I believe you can always understand, can't you?
I remember that the first chapter of compulsory mathematics in senior one is about set, which was very simple at first, just a few things, definition, representation, basic operation and some matters needing attention. But the questioner is too clever, and the problem comes from this. We will waste a lot of experience when doing the problem, and it is still incorrect in the end. Think about the problems you have done, indeed. There are at least two groups of problems, often related to a quadratic equation. There are solutions, no solutions, equal real roots, two unequal roots, two positive and negative roots, or both positive and negative roots, and so on, so as to find quadratic coefficients, linear coefficients, constant terms, and so on. Combining the intersection and complement of sets, we can get the unknown set from the known set (note here that we must check when doing this kind of problem). More importantly, the most shameless thing is that some problems have to be discussed separately. When doing this kind of problems, we must consider comprehensively and sum up experience. Senior three will do more classification questions.
Having said that, in fact, what I want to say is that the basic things of mathematics are very simple, but it is difficult to combine. It doesn't matter whether it's hard or not now. Lay a good foundation, understand the most basic things, and then improve a little, you can't eat hot tofu in a hurry.
I suggest that you should have a notebook. What notebook? A notebook, a set of wrong questions, a set of fine questions, all in one. It depends on your distribution and irrationality. That's how I got it. In fact, as we all know, not all wrong questions should be included in the wrong set. Just write down some typical ones. If you are careless, I think you should know how to do it. The so-called intensive problem set is to write down some questions on it (good problem-solving skills).
Physics is still very simple. Chemistry was a little difficult to learn just now, but you will understand it soon, and you will find it is actually very simple.
It is getting late. Tomorrow we will talk about chemistry and physics.
Physical compulsory one is actually the whole high school stage, which is relatively simple. It is nothing more than uniform linear motion, force analysis, application of Newton's law and some experiments.
There is nothing to say about sensory physics, mainly to understand the application formula, understand the generation of force and analyze it. The above two are related by Newton's law.
Experiment: Acceleration is measured by point timer, and paper tape is generally treated by differential method, subsection method or direct calculation method. It is verified that the parallelogram rule is nothing more than the influence of the node position and included angle of the rubber band on the experiment. In order to verify Newton's second law, we mainly draw pictures and process them. Attention should be paid to drawing the images of A and 1/m here, and you should also see clearly when processing the images.
It is easy to make mistakes in chasing problems when doing problems with uniform changes. There are too many roads inside, so you should be careful.
For example, a person is riding a bicycle at a speed of 3m/s, when a truck with uniform acceleration passes by him at a speed of 10m/s with an acceleration of 5m/s? How long does it take people to catch up with the van? What is the average speed of the truck during this process?
Do more questions in this area, and you will find out what needs attention, and then summarize.
My question above, the van stopped before people caught up with it.
Some problems are catching up before the car stops, and some problems are catching up just after the car stops. As mentioned earlier, if the bicycle speed is changed to 5m/s, it will just catch up and stop, but when the bicycle speed is greater than 5m/s, it will not stop.
In some problems, the car slows down first and then accelerates, and the speed may not drop to zero. For example, change the above question to
When the truck stops, the speed will be 1m/s? The acceleration is accelerating. Ask others if they can get on the truck. How long will it take if they can make it?
And some problems are that the car slows down first and then accelerates in the opposite direction. If the above question is changed to
When the truck stops, the speed will be 1m/s? The acceleration is reversed, asking when people and trucks will meet again.
Free fall, just like dealing with paper tape, feels nothing to say.
You should be quite familiar with the average speed in the future, the speed at the middle moment and the speed at the middle displacement. Uniform variable speed linear motion, initial velocity is zero, time ratio is the same and unique, and displacement ratio at the same time, just remember this.
Force analysis is mainly about those forces and those simple models. I think this should be no problem. If you have any questions, I suggest you choose liberal arts.
There is a critical point in stress analysis, so I won't talk about it here. Specific analysis of the specific situation, you have to ask teachers or classmates if there are any resources that are useless and wasted.
Niuer's Law is based on force analysis. After the force analysis, it is very simple to find the acceleration.
Pay attention to some problems, such as: when a slider with a certain initial speed slides on a ramp, it will slow down first, but when it reaches zero, the friction will reverse instantly, which means that it is necessary to judge the relationship between friction and the component of gravity along the ramp.
Let's talk about chemistry I think chemistry is simpler.
Chemistry is a compulsory course. The first chapter introduces the quantity of substances, and matches a solution with a certain concentration with the experiment. There are too many problems involved, especially sulfuric acid, which is the worst thing.
Followed by metals: sodium, aluminum, iron, magnesium, copper, zinc and so on.
Na is very simple, mainly the phenomenon and explanation of the reaction between Na and water. The combustion of sodium, the color of flame and the color properties and uses of products. The relationship between Na2CO3 and NaHCO3 changes. Note: Na2CO3 in the air will not produce NaHCO3 in the end.
The transformation of Fe triangle, Fe2+ and Fe3+, how to verify the existence of these two ions in solution.
All the culprits are metaaluminate.
Magnesium can react with carbon dioxide.
Why can't sodium replace aluminum, iron, magnesium, copper and zinc?
Non-metals: silicon, sulfur, chlorine, nitrogen, etc.
Remember that.
Redox reaction, ionic equation.
Ionic equation is fine, but the redox reaction is hard to say, which is also the most important.
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Long time no see. I forgot a lot of things. sorry
I hope my answer is helpful to you.