"y=mx+b" is the formula of a straight line drawn on Cartesian coordinate system in which "y" is the vertical axis and "x" the horizontal axis.
In this formula:
y tells us how far up the line goes
x tells us how far along
m is the Slope or Gradient i.e. how steep the line is
b is the Y-intercept i.e. where the line crosses the Y axis
The X and Y intercepts and the Slope are called the line properties. We shall now graph the line x-4y+2 = 0 and calculate its properties
<u>Calculate the Y-intercept:</u>
Notice that when x = 0 the value of y is 1/2 so this line "cuts" the y axis at y= 0.50000
y-intercept = 2/4 = 1/2 = 0.50000
<u>Calculate the X-intercept:</u>
When y = 0 the value of x is -2/1 Our line therefore "cuts" the x axis at x=-2.00000
x-intercept = -2/1 = -2.00000
<u>Calculate the slope:</u>
Slope is defined as the change in y divided by the change in x. We note that for x=0, the value of y is 0.500 and for x=2.000, the value of y is 1.000. So, for a change of 2.000 in x (The change in x is sometimes referred to as "RUN") we get a change of 1.000 - 0.500 = 0.500 in y. (The change in y is sometimes referred to as "RISE" and the Slope is m = RISE / RUN)
Let the height of the tree be x, then 18 inches / 3 feet 9 inches = x / 21 feet 3 inches 18 inches / 45 inches = x / 255 inches 45x = 18 x 255 = 4590 x = 4590 / 45 = 102
Therefore, the tree is 102 inches = 8 feet, 6 inches tall