![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
Proportion is divided into positive proportion and negative proportion
No, proportion is an expression that two ratios are equal, and positive and negative proportion is for two related quantities
1. The surface area of a cube is in direct proportion to the area of one of its faces ()
2. For a bag of rice, the amount eaten is out of proportion to the amount left ()
3. One twelfth of the number a is equal to two fifths of the number B, and the number a is not in proportion to the number B ()
4. If y = 2.8x, then y is proportional to X ()
5. The ratio of circumference to width of a square is 8:1, so the ratio of length to circumference is 1:3 ()
6. Two related quantities, either positive or negative ()
7. If a figure is enlarged by 2:1, that is to say, each side is enlarged by 2 times of the original ()
2、 Choice
1. The formula for X and y to be proportional is ()
A,5xy=26 B,y=0.6x C,3x+2=18
1. The surface area of a cube is in direct proportion to the area of one of its faces
2. For a bag of rice, the amount eaten is out of proportion to the amount left
3. One twelfth of the number a is equal to two fifths of the number B, and the number a is not in proportion to the number B (wrong)
4. If y = 2.8x, then y is in direct proportion to X
5. The ratio of circumference to width of a square is 8:1, so the ratio of length to circumference is 1:3 (wrong)
6. Two related quantities, either positive or negative (wrong)
7. If a figure is enlarged by 2:1, that is to say, each side is enlarged by 2 times of the original
2、 Choice
1. The formula for X and y to be proportional is (b)
A,5xy=26 B,y=0.6x C,3x+2=18
If the two quantities are not in positive proportion, they are in inverse proportion
The diameter of a circle is in direct proportion to its circumference ()
If four fifths of a is equal to seven fifths of B, then a is 4 to 7
If the two quantities are not in positive proportion, they are in inverse proportion
The diameter of a circle is in direct proportion to its circumference!
If four fifths of a is equal to seven fifths of B, then a is more wrong than B = 4 to 7
RELATED INFORMATIONS
- 1. Fill in the blanks and judgment questions of positive and negative proportion exercises, 1. 35: () = 20 △ 16 = = ()% = () (fill in decimal) 2. Because x = 2Y, X: y = (): (), X is proportional to y 3. The side area of a cylinder is fixed, and the circumference of its bottom is proportional to its height 4. The circumference of a circle is proportional to its radius 5. The ratio of edge length of two cubes is 1:2, and the ratio of their volume is (): () 6. With the same tiles, shop 64 square meters to 320, as such, shop 20 square meters to () pieces 1. The ratio of number a to number B is 3:4, and the number a is 3 / 4 of the number B 2. When 10 grams of pesticide are dissolved in 90 grams of water, the ratio of pesticide to water is 9:1 3. In the 800 meter race, the speed of an athlete is inversely proportional to the time spent 4. A parallelogram has a certain area, and its base and height are in direct proportion 5. The weight of peanut is proportional to the weight of peanut oil 6. If the actual distance is constant, the distance on the map is in direct proportion to the scale 7. The volume of a cube is constant, and the area of its base is inversely proportional to its height 8. The total amount of subscription to Hebi daily is proportional to the number of copies 9. When the total number of parts is fixed, the number of produced parts is inversely proportional to the number of unproductive parts 10. A person's weight is directly proportional to his height 11. The circumference of a rectangle is fixed, and its length and width are in inverse proportion 12. The total amount of water is fixed, and the amount of water used is inversely proportional to the amount of water remaining 13. The radius of a circle is proportional to its area 14. A scale is a ratio, so it has no unit
- 2. Mathematical inverse proportional function It is planned to build a rectangular lawn with an area of 600. The functional relationship between Y length and x width? Y: x = 3:2, what are the length and width respectively? It's all wrong
- 3. A problem of inverse proportion function As shown in the figure, the image of the positive scale function y = 1 / 2 x and the image of the inverse scale function y = K / X (K ≠ 0) in the first quadrant intersect at point a, cross point a to make a vertical line of the X axis, the perpendicular foot is m, and the known area of △ OAM is 1, (1) Finding the analytic expression of inverse proportion function (2) If B is an inverse scale function, and the abscissa of point B is 1 at the point on the first quadrant image (point B does not coincide with point a), find a point P on the X axis to minimize PA + Pb
- 4. Judging inverse proportion function If the area of the trapezoid is fixed, is the median line inversely proportional to the height?
- 5. A judgment question A project can be completed in 6 days with the cooperation of Party A and Party B. If Party A does it alone in 10 days, then Party B does it alone in 15 days
- 6. Ten mathematical judgment questions 1. An equation with unknowns is called an equation () 2. N is a natural number, and 2n is an even number () 3. Because 22 = 2 × 2, A2 = a × 2 () 4. 56-x < 0.7 is not equation () 5、c +c=2c,a×a=2a.（ ） 6. An equation must be an equation, and an equation does not have to be an equation 7、a²＞a×2 .( ) 8. When a = 3, the cube of a = a × 3 9. The process of solving an equation is called solving an equation 10. 4m-12 = 0 is the equation
- 7. As shown in the figure, it is known that the image of the inverse scale function Y1 = K1X and the image of the primary function y2 = k2x + B intersect at two points a and B, and a (2, n), B (- 1, - 2). (1) find the relationship between the inverse scale function and the primary function; (2) use the image to write directly when x is in what range, Y1 > Y2
- 8. It is known that y is the inverse proportional function of X. when x = 3, y = 2, then the functional relation between Y and X is______ ．
- 9. As shown in the figure, points a (m, M + 1) and B (M + 3, m-1) are all on the image of inverse scale function y = KX. (1) find the value of M and K; (2) if M is a point on the x-axis, n is a point on the y-axis, and the quadrilateral with points a, B, m and N as vertices is a parallelogram, try to find the functional expression of straight line Mn
- 10. As shown in the figure, given the points a (4, m) and B (- 1, n) on the image with inverse scale function y = 8x, the line AB intersects the x-axis and y-axis at two points c and D respectively. (1) find the analytical formula of the line AB; (2) find the coordinates of two points c and D; (3) what is s △ AOC: s △ BOD?
- 11. A problem of positive proportion function in the second grade of junior high school, It is known that y + m is proportional to x-n, and when x = 2, y = 3; when x = 1, y = - 5. Find the value of y when x = - 1 I need it tonight
- 12. If the images of positive scale function and linear function pass through point m (3,4) If the images of the positive scale function and the first-order function pass through the point m (3,4), and the area between the images of the positive scale function and the first-order function and the Y axis is equal to 15 / 2, the analytic expressions of the two functions are obtained
- 13. Given that the image of positive scale function y = KX passes through (2,3a) and (a, - 6) (a is greater than 0), the value of X when y = 3 is obtained
- 14. The expression of positive scale function of image passing through (1,2) is______ ．
- 15. When the image with positive scale function y = 5x passes through the first quadrant and the second quadrant, point (0,) and point (1,) are on the image, y The image with positive scale function y = 5x passes through the second image Point (0,) and point (1,) are in their image Y increases with the increase of X?
- 16. If the inverse scale function y = KX passes through (- 3,2), then the image______ Quadrant
- 17. Given the function y = (M-3) x ^ (m ^ 2-10), when what is the value of M, it is an inverse scale function? In which quadrant is his image located
- 18. Let the function y = (m-2) x * M-4 be an inverse scale function. (1) find the value of M. (2) draw the image of this function and point out which quadrant is its image located? Let y = (m-2) x * M-4 be an inverse proportional function (1) Finding the value of M (2) Draw an image of this function and point out which quadrants its image is in? (3) If the line y = KX intersects with the image of this function at two points a and B, and the ordinate of point a is 2, it is the solution set of the inequality (m-2) x * M-4 > KX about X
- 19. Given a positive proportional function and a first-order function, their images pass through the point P (- 3,3), and the image of the first-order function intersects with the Y axis at the point Q (0, - 2), the analytic expressions of the two functions are obtained
- 20. A function image translation problem How is the image of F (x) translated from the image of F (x-1)? Let's take an example,