Question

Consider the linear equations 7x-14y=9, 5x-10y=a. For what value of a, the pair of linear equations will have a unique solution?

Answer 1

Answer:

Step-by-step explanation:

Slopes of parallel lines are the same.  

7x - 14y = 9 ⇔ y = $\frac{1}{2}$ x - $\frac{9}{14}$

5x - 10y = a ⇔ y = $\frac{1}{2}$ x - $\frac{a}{10}$

$\left \{ {{7x-14y=9} \atop {5x-10y=a}} \right.$

The system of the linear equations has no solutions for any value of "a" except of a = - $\frac{9}{14}$ then system has infinitely many solutions.