Question

Which ordered pair is not a solution of 5x-4y=7? Explain

Answer 1

To find the solutions (and those that are not solutions), we first need to solve the equation for y, then substitute the value of x in the resulting expression, and then get the value for y.

We can also substitute the value for x and y in the expression. Those values for which the expression is equal to 7 are a solution for the equation.

First Case: (-9, -13)

Then we have:

`5(-9)-4(-13)=7`

Then, this pair is a solution.

Second Case: (-5, -9)

`5\cdot(-5)-4\cdot(-9)=11`

Then, this pair is NOT a solution.

Third Case: (7, 7)

`5\cdot(7)-4\cdot(7)=7`

This pair is a solution.

Fourth Case: (11, 12)

`5\cdot(11)-4\cdot(12)=7`

Therefore, the ordered pair that is NOT a solution of 5x - 4y = 7 is (-5, -9) (option B).