2.d has no focus. For example, if the inverse scale is a graph with one or three quadrants, then the straight line can only take two or four quadrants, that is, the two k symbols are different.
4. The function A is increasing on the negative semi-axis of X, that is to say, the graph has two or four quadrants, that is, k is negative, and the focus of the function and coordinates is on the negative semi-axis, that is, it is only the first quadrant.
At first, I thought the same thing as you. Well, forgive me for not doing the problem for a long time. Later, I found that the required straight line, that is, y=kx+b, is smaller than y=0, that is, the part below the X axis, but larger than y=2x, that is, the part above the straight line. Then it is obvious from the figure that only the line segment AB satisfies the condition, and the range of the line segment X is known as B.
6. This is really difficult. Although it took me some time to work it out, it was totally unnecessary. For multiple-choice questions, just look at the rules. Then I'll just say the simple judgment method. First of all, when B and E overlap, the area must be 0, so the overlapping area of CE at the endpoint is also 0. In fact, the trend is to get bigger first and then smaller, but the change is not uniform, so the answer must be B or D. It seems that you still choose D with some understanding, but in this case, the area is nothing more than a higher-order function of X, and there are no other constants, so it must be symmetrical and not affected by constants, so choose B, which is actually the real functional relationship of this problem.
How to do this, you can use the ordinary method. Starting from 1-x, the area formula is gradually worked out by triangle similarity, but it is more troublesome. The simple method is to make an auxiliary line, take a little G between AB, and make BEG form a right-angled isosceles triangle, that is, EG and BC form a 45-degree angle, then AEG and CEF are congruent, angular, and the middle side is equal to AG and EC = 1-X, and you will understand later.
Ok, go to bed after answering.