Question

for what value of k is the pair of linear equation X+2y=7 and 3x-ky=21 has infinitely many solutions​

Answer 1

Step-by-step explanation:

well, for infinite many solution, you should have,

a1/a2=b1/b2=c1/c2

in equation 1 , a1=1,b1=2, c1=7

in equation 2, a2=3, b2=-k, c2=21

so, putting the values of a1,b1,c1and

a2, b2, c2 in the above condition we get,

1/3=2/-k=7/21

=> 1/3=2/-k =1/3

=> 1/3=2/-k

=> 6= -k.

=> k=-6.