Plot the function y = 2x-4. a) whether point A (-20; -70) belongs to the graph
Plot the function y = 2x-4. a) whether point A (-20; -70) belongs to the graph; b) Indicate with the help of the graph the value of x at which. y = 6, y = 0
y = 2x – 4. This is a linear function, the graph will be a straight line.
A straight line can be drawn from two points.
Let’s take arbitrary values of x:
x = 0; y = 2 * 0 – 4 = 0 – 4 = -4. Point (0; -4).
x = 3; y = 2 * 3 – 4 = 6 – 4 = 2. Point (3; 2).
We build a coordinate plane, mark two points and connect them along a ruler. The function graph is built.
a) According to the graph, you cannot see whether point A (-20; -70) belongs to the graph of the function, so we substitute the value of x and y into the equation of the straight line and check the equality.
x = -20; y = -70.
-70 = 2 * (-20) – 4; -70 = -40 – 4; -70 = -44 (incorrect).
Point A does not belong to the graph of the function.
b) We look at the graph for the value of x, at which y = 6: x = 5;
y = 0: x = 2.