Question

the number of value of k for which the system of equation x+y=2,kx+y=4,x+ky=5 has at least in solution is

Answer 1

Hello....

x+y=2...(1)⇒y=2-x
kx+y=4....2)
⇒kx+2−x=4
(k−1)x=2 ......(2)
x+ky=5...(3)
x+k(2−x)=5
x+2k−kx= 5
minus(k−1)x+2k=5
−2+2k=5 [from eq(2)]
2k=5+2
2k=7⇒k=7/2