The graph of the function y = kx + b intersects the coordinate axes at points A (0; -2) and B (4; 6). Find the value of k and b.
In the problem statement, it is necessary to correct “at points A (0; -2) and B (4; 6)” by “at points A (0; -2) and B (4; 0)”.
Decision.
According to the condition of the problem, the graph of the function y = kx + b intersects the ordinate axis at point A (0; -2).
Substituting the values x = 0 and y = -2 in the equation of this function, we get:
-2 = k * 0 + b.
From this ratio we find b:
b = -2.
It is also known that the graph of this function crosses the abscissa at point B (4; 0).
Substituting the values x = 4 and y = 0, as well as the found value b = -2 into the equation of this function, we get:
0 = k * 4 – 2.
We solve the resulting equation and find k:
k * 4 = 2;
k = 2/4;
k = 0.5.
Thus, the graph of this function intersects the coordinate axes at points A (0; -2) and B (4; 0) at k = 0.5 and b = -2.
Answer: k = 0.5; b = -2.