plz help

The straight line l passes through the point A (1, −3) and the point B (7, 5).
a Find an equation of line l. (3)
The line m has the equation 4x + y − 17 = 0 and intersects l at the point C.
b Show that C is the mid-point of AB. (4)
c Show that the straight line perpendicular to m which passes through the point C also
passes through the origin. (4)

plz solve it. thank you. :smile:

i ll reward you with rep.

Reply 1

Chewwy

i)

gradient = dy/dx = (5 - -3)/(7 - 1) = 4/3

y = (4/3)x + c

(1, -3)

-3 = 4/3 + c

c = -13/3

y = (4/3)x - 13/3

3y = 4x - 13

ii)

4x + (4/3)x - 13/3 - 17 = 0

(16/3)x = 64/3
x = 4

y = 17 - 4x
y = 17 - 4(4)
y = 1

check and see (4, 1) is midpoint.

iii)

4x + y − 17 = 0

y = 17 - 4x

perp. grad = -1/(-4) = 1/4

y = x/4 + c

(4, 1)

1 = 4/4 + c

c = 0

Reply 2

IZZY!