A common way to write a linear function is in the slope-intercept form, y= mx+ b. The slope m is the rate of change of the function.
m=Change in $y$/Change in $x$
Let's change the order of the coordinates and look into the rate of change for our data.
In the given mapping we can see that for each increase by 1 unit for x, the values for y decrease by 2. This rate of change means that our function has a slope of -2. We can also see this using the Slope Formula and two of the points.
Let's substitute - 2 for m in the equation.
y= mx+ b ⇒ y= -2x+ b
The y-intercept b is the point where x= 0. This point we have been given in the mapping.
We can substitute this value into the slope-intercept form, and then we have our equation.
y=-2x+ 1
