The line passing through the points (-1,6) and (4,x) has gradient -2. Find the value of x. Show working out please.
Line with slope a through a point (x1,y1) has the equation:
y=a(x-x1)+y1
Putting a=-2, (x1,y1)=-1,6), we get the line as:
y=-2(x-(-1))+6 or
y=-2x+4 ....(1)
Substitute x=4 in equation 1 to find the value of y, which is the required unknown.