Question

Suppose the system of linear equations has no solution. Which is NOT a possible value of the constant for the second equation?

6x + 9y = 15
2x + 3y = __

A) 5
B) 10
C) 15
D) 20

Answer 1

A) 5

Explanation:

The coefficients of the second equation are 1/3 of those of the first equation. If the constant of the second equation is also 1/3 of the constant of the first equation, then the equations are dependent, and will have an infinite number of solutions.

The constant must be something other than 1/3·15 = 5 to make the equations inconsistent, having no solutions.