Question

Select the best possible first step to solving the system by first eliminating the x variable.

3x + 5y = 1
2x + 4y = −4

Answer 1

The best possible first step would be to multiply equation one by 4 and equation by 5 that would eliminate the y and allow you to solve for x.

In essence, 4 × (3x + 5y = 1) eq1
5 × (2x + 4y = -4) eq2

thus giving rise to 12x + 20y = 4 eq1 × 4
10x +20y = -20 eq2 × 5

You can then just subtract one equation from the other
For example, (12x + 20y = 4) - ( 10x +20y = -20 )

12x - 10x + 20y - 20y = 4 - (-20)
2x = 24
x = 12

Answer 2

Explanation:

3x + 5y = 1

2x + 4y = −4

when we need to eliminate a variable we first need to make there coefficient same . (with opposite sign )

here we are asked to eliminate the variable x s we first need to make its coefficient equal

multiply first equation by 2 and second equation by -3 we get

3x + 5y = 1 )·2 => 6x+10y =2

2x + 4y = −4 )·-3 =>-6x -12y = 12

so first step to eliminate the x variable can be multiply first equation by 2 and second by -3 .