Respuesta :
Answer:
k=3 is your answer
Step-by-step explanation:
given equation :
9x²+12xy+(k+1)y²=0
comparing above equation with
ax²+2hxy+by²
we get
a=9
h=12/2=6
b=k+1
since lines are coincident
ø=0
Tan0=±[2√(h²-ab)]/(a+b)
we get
h²=ab
6²=9(k+1)
36/9=k+1
4=k+1
k=4-1=3
