Show and explain how replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions as the one shown.

8x + 7y = 39

4x – 14y = –68

Question

Show and explain how replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions as the one shown.

8x + 7y = 39

4x – 14y = –68

justjm · Answer

The description must be some alien way of saying to perform elimination.

Multiply the first equation by 2, cancel out the 14 and -14 by adding the equation, then isolate x. Then plug in x into one of the original equations in the system (it doesn't matter which one, I like to do both as a justification strategy). Isolate y and you get your solution (x,y)