The following functions: ① y = 2x + 3; ② y = 3 (3-x); ③ y = 3x-x2; ④ y = − X3; ⑤ y = 5 A. ①②③④⑤B. ②④C. ①③⑤D. ②④⑤

According to the definition of a function, we can see that: ① y = 2x + 3 is not a function because the number of independent variables is not 1; ② y = 3 (3-x) is a function; ③ y = 3x-x2 is not a function because the number of independent variables is not 1; ④ y = − X3 is a function; ⑤ y = 5 is not a function, let alone a function, so a function has a total of ② ④

RELATED INFORMATIONS

1. The following functions are: 1. Y = - 3x + 4 2. Y = 7 / 5x 3. Y = 1 + 2 / x 4. Y = x & # 178; + 25. Y = X-1 / 2, where is a linear function?
2. : when x takes what value, the value of the following function is zero (1) y = - 5 + 3x (2) y = 2x & # 178; - 5x + 3 (3) y = x-3 of X-1 The point is the third question. Because I don't understand. It's better to be clear
3. Find the maximum value of the following function y = 2x & # 178; - 3x-5, y = - X & # 178; - 3x + 7 Find the maximum value of the following functions y＝2x²－3x－5 y=-x²－3x＋7
4. As shown in the figure, it is known that the image with positive scale function y = 3 / 4x and the image with inverse scale function y = K / X intersect at point a, and make a straight line ab ‖ Y axis through point a, and intersect X axis at point B, OB = 4 , m (m, n) is a moving point on the inverse scale function image, where 0 < n < 4 (1) The expression of inverse proportion function (2) When om = OA, find the value of M + n (3) Make a straight line MC ∥ X axis through point m, intersect Y axis with point C, intersect a straight line AB at point D. when the area of quad OADM is 12, please judge the size relationship between cm and DM, and explain the reason
5. The image with known positive scale function y = 1 / 4x passes through point a (2, a) (1) The analytic expression of inverse scale function image passing through point a (2) If any point P in the image of the inverse scale function is taken as the PA ⊥ X axis and Pb ⊥ Y axis, the area of the rectangular OAPB can be calculated
6. When x > 1, the value range of Y is 0
7. The image of a positive scale function passes through (2, - 3), and its relation is a.y = - 3 / 2x b.y = 2 / 3x C.Y = 3 / 2x D.Y = - 2 / 3x
8. When k=__ The function y = 2x ^ (k ^ 2-3x-3) is a positive proportional function
9. In the function y = 1 / 3 x, y = 1 / 2 x + 3, y = 1 / 3 x, y = 2 [x-3], the positive proportion function is [] The linear function is []
10. Is y = - 3x square a positive proportional function?
11. Among the following functions, the first-order function is (1) y = - 8x (2) y = 5x & # 178; + 6 (3) y = - 8 / X (4) y = - 0.5x-1 (5) y = K & # 178; X + 6 (k is a constant)
12. If Y-2 and X-2 are in positive proportion, then the functional relationship between Y and X is () A. a linear function may also be a positive proportion function B. a positive proportion function c. a linear function
13. If we know that y = KX + K-3 is a positive proportional function, then its analytical expression is
14. It is known that the image of positive scale function y = KX passes through point P (1,2), as shown in the figure. (1) find the analytic expression of the positive scale function; (2) translate the image of the positive scale function to the right four units, and find the analytic expression of the translated straight line
15. It is known that the positive proportional function y = KX (K ≠ 0) and the y of points (2, - 3) on the function increase or decrease with the increase of X
16. The positive proportional function y = KX passes through point a (3, - 4) to find the value of K
17. The image of the linear function y = KX + B (K ≠ 0, B ≠ 0) always passes through the point (0,?) And (0,?) Two points, the positive proportion function y = KX (K ≠ 0) always passes through (0,?) And (1,?) Two points
18. Is the positive scale function y = KX + b k necessarily greater than zero? If K is less than zero, y decreases with the increase of X Is that still a positive ratio?
19. Let y = (K + 2) x + K be the square of - 9=___ It is a positive proportional function passing through two or four quadrants
20. How many quadrants must the image of the positive scale function y = (K & # 178; + 1) x (k is a constant, K ≠ 0) pass through