For which values of k does have no solution "kx + y = 1" "x + ky = 1"

When they are paralell

hum

kx+y=1

x+ky=1

if k=0 then they intersect at (1,1)

if k=1, they are the same equation

they have to be paralell, so same slope

solve for y to get y=mx+b

y=-kx+1 and

y=-x/k+1/k

the slopes are - k and - 1/k

slopes must be the same

-k=-1/k

times - 1 both sides

k=1/k

times k both sides

k^2=1

k=1 or - 1

1 doesn't work so k=-1

answer is k=-1