We can find the equation of any line by finding the slope and y-intercept. Then the equation of the line can be written in slope-intercept form, y = mx+b.

Write the equation of the line in slope-intercept form given the following , then graph it.

a) a slope of 3 and passes through point (2,1) y = mx + b y = 3x + b 1 = 3(2) + b 1 = 6 + b -5 = b Thus the equation of the line is: y = 3x - 5

b) passes through points (2,6) & (-4,-6) m = (-6-6) / (-4-2) m = -12 / -6 m = 2 y = mx + b y = 2x + b 6 = 2(2) + b 6 = 4 + b 2 = b Thus the equation of the line is: y = 2x + 2

Try graphing both equations. Go to the Graph applet below. To graph your two equations:

Type in the b, your y-intercept. Type in the m, your slope. Hit Enter. Click Clear and try another. Note: Fractions & Decimals wont work.

Write the equation of the line given the following graph.

a) Take any two points from the line in the given graph. We will choose (1,1) & (-1,-3.) Then the procedure is the same as above.

m = (-3-1) / (-1-1) m = -4 / -2 m = 2 y = mx + b y = 2x + b 1 = 2(1) + b 1 = 2 + b -1 = b Thus the equation of the line is: y = 2x - 1