Question

if line x+2=0 coincides with one of the lines represented by the equation x^2+2xy+4y+k=0 then show that k=-4​

Answer 1

Answer:

Given,

x+2=0

or, x=-2

the given equation is x^2+2xy+4y+k=0__________(1)

since the line is parallel to the y axis, y=0.

Now, putting the value of x and y =0 in the equation (1) we get,

(-2)^2+k=0

or, 4+k=0

Or, k=-4[proved]