Question

Number of values of k for which pair of linear equations 7x – y = 5 and 21x – 3y = k have unique solutions (A) 0 (B)1 (C) infinite (D) None of these​

Answer 1

your question is wrong check it .

instead of unique solutions parallel will come

a1/a2=b1/b2≠c1/c2

7/21=1/3≠ 5/k

1/3≠ 5/k

k≠15