The image of a positive scale function passes through a point (- 2,8) and passes through a point a on the image to form a vertical line of y-axis. The vertical foot is B (0,6)

Analysis: for the positive proportion function y = KX, the value of K can be determined by telling a set of corresponding values. Therefore, k = - 4 can be obtained. Because the vertical line of Y axis is made through point a (parallel to X axis), the ordinate of point B is the same as that of point a, so the ordinate of point a is also 6. Substituting it into a group, the abscissa is - 1.5, that is, a (- 1.5,6). The area of triangle can be obtained by transforming the coordinates of point into the length of corresponding line segment
Let the analytic expression of positive scale function be y = KX, because (- 2,8) is on the image, so - 2K = 8, the solution is k = - 4
Since AB is perpendicular to the Y axis, the coordinates of point a are the same as those of point B. let a be (a, 6), and substitute y = - 4x to get a = - 1.5, so the coordinates of point a are (- 1.5, 6)
In RT △ OAB, because a (- 1.5,6), B (0,6) so ob = 6, ab = 1.5, so the area of △ OAB= AB.OB/2=1 .5*6/2=4.5.

The image of a positive scale function passes through a point (- 2,8) and passes through a point a on the image as a vertical line of the y-axis. The vertical foot is B (0, - 6)
What is the area of AB?

(1) First of all, according to the point (- 2,8), the positive scale function is y = - 4x, which brings the ordinate - 6 of point a in, so the coordinate of point a is (1.5, - 6)
(2)S△OAB=1.5×6÷2=4.5

The area of the triangle formed by the first-order function y = 2x + B and two coordinate axes is 2, and the value of B can be obtained

Plus or minus 2 times root sign 2
Process: function passing point (0, b), (- B / 2,0)
Absolute value of S = 0.5 * b * (- B / 2)
The solution is b = plus or minus 2 times the root sign 2

The image of a positive scale function passes through a point (- 2,8) and passes through a point a on the image to form a vertical line of y-axis. The vertical foot is B (0,6)