Question

To eliminate the y-terms and solve for x in the fewest steps, by which constants should the equations be multiplied by before adding the equations together?

First Equation: 5x − 4y = 28

Second equation: 3x - 9y = 30

The first equation should be multiplied by 3 and the second equation by 5.
The first equation should be multiplied by 3 and the second equation by −5.
The first equation should be multiplied by 9 and the second equation by 4.
The first equation should be multiplied by 9 and the second equation by −4

Answer 1

The first equation should be multiplied by 9 and the second equation by −4

Explanation:

Given the simultaneous equation

First Equation: 5x − 4y = 28

Second equation: 3x - 9y = 30

In order to eliminate y, we must make the coefficient of x in both expression to be equal.

To do that the first equation should be multiplied by 9 (negative value of the coefficient of y in equation 2)and the second equation by -4( (coefficient of y in equation 1)