Question

Number of values of k for which pair of linear equations 7x – y = 5 and 21x – 3y = k have unique solutions

Answer 1

Step-by-step explanation:

Your Question is wrong, Instead of unique solutions Parallel will be Applied because this Equation for parallel Solutions.

The pair of linear Equation have Parallel solutions

i.e., a1/a2 = b1/b2 ≠ c1/c2

The linear Equation which is in form of

ax + by + c = 0 which is 7x - y - 5 = 0 and

21x - 3y - k = 0

a1 = 7, a2 = 21, b1 = -1, b2 = -3, c1 = -5,

c2 = -k

∵ a1/a2 = b1/b2 ≠ c1/c2

=> 7/21 = -1/-3 ≠ -5/-k

=> 1/3 ≠ 5/k

=> k ≠ 15.