Question

y can be eliminated from the system of equations: 4x + 7y = 12 (3) x + y = 4 by adding the equations after multiplying the second equation by: a) -4 b) 4 c) -7 d) 7 e) none of these

Answer 1

Therefore,

The Correct option is C) -7

Explanation:

Given:

`4x+7y=12` ...........Equation ( 1 )

`3x+y=4` ...........Equation ( 2 )

To Find:

The Correct option for Eliminating "y"

Solution:

So to Eliminate "y" we need to add the equations after multiplying the second equation by " - 7 " (i.e option C) -7 )

So Equation ( 2 ) become

`-7* (3x+y)=-7* 4`

Applying Distributive Property we get

`-21x-7y=-28`

Now by adding +7y and -7y will get eliminate and we get

`-17x=-16\\\\17x=16`

Therefore,

The Correct option is C) -7