A straight line passes through the point (2,1) and has a gradient of 3. Find the co-ordinates where the line crosses the x and y axes

m=3

y1=1

x1=2

y-y1=m(x-x1)

y-1=3(x-2)

y-1=3x-6

y=3x-5

at the x-axis, y=0. 

Sub in to find the x co-ordinate:

0=3x-5

x=5/3. Hence the co-ordinates at which the line crosses the x axis are (5/3,0)

at the y-axis, x=0. 

‘Sub in to find the y co-ordinate 

y=(3X0)-5

=-5. Hence the co-ordinates at which the line crosses the y-axis are (0,-5)