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Question 21648: please help me solve " what the slope-intercept form of of the equation of a line with slope 5 and y-intercept -8?"
Answer by glabow(165)   (Show Source):
You can put this solution on YOUR website! The slope-intercept form for the equation of a line contains two pieces of information: the slope and the y-intercept.
The slope tells how y changes when there is a change in x. For example, a slope of 3 means that for each change in x of 1 unit, y changes 3 units. A slope of -3 would mean that for each change in x of 1 unit, y changes -3 units. This is written algebraicly as y = mx, where m is the slope. y = 3x is the equation of a line that has a slope of 3. Look at a little table for various values of x:
y.....x
3.....1
6.....2
9.....3
Each time x changes by 1 (1 to 2, 2 to 3), y changed by 3 (3 to 6, 6 to 9). This is because y is always 3 times whatever x is.
Next, the y-intercept tells at what point the line crosses the y axis. That is, what is the value of y when x is zero? Well, since this is a single fixed place on the y-axis the equation of y = a gives that information. If the line crosses the y-axis at 2, then the equation would be y = 2. If it crosses at -7, then the equation would be y = -7.
The combination of these two pieces of information gives an equation of  .
For the information you had (slope of 5 and intercept of -8) the equation is
y = 5x - 8.
Simple, no?
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