A line joins 2 points (2,9) and (5,4). Calculate the gradient of the straight line and then write down the equation of the straight line.

The first thing to do is to look at the points given and decide if you are going to get a negative or positive gradient. We can determine, from inspection that the gradient will be negative because as the x value increases the y value decreases along the line. So we can calculate the gradient m=(y2-y1)/(x2-x1) m=5-2/4-9 m=3/-5 m=-3/5 Now we can calculate the equation of the straight line. y=mx+c pick one of the co-ordinates and sub in their x and y values I'll use (5,4) 4=-3/5*5+c 4=-3+c c=7 y=(-3/5)x+7