The equation of the line passing through (1,-11) and (-4,5) can be expressed in the form x / a + y / b = 1
Find a.
+130413 y = mx + b
m = slope = (5- -11) /( -4-1) = -16/5
Using the slope and (1,-11) we have
y = (-16/5) (x -1) -11
y = (-16/5)x + 16/5 - 11
y = (-16/5)x - 39/5
(16/5)x + y = -39/5 ...... multiply through by (-5/39)
(-16/39)x - (5/39)y = 1
And we can write
x / ( -39/16) + y / ( -39/5) = 1
a = -39/16
