How do you solve this system of equations using the addition method: 4 x − y = − 4 ; 5 x + 2 y = − 18 ? Algebra 1 Answer
IDKwhatName Jun 30, 2017 x = − 2 , y = − 4 Explanation: Right now, you have: 4 x − y = − 4
5 x + 2 y = − 18 To make this easier, you must get rid of one variable, in this case I will remove y , to do this you must make the y-values in both equations the same. To do this, I will multiply the whole of 4 x − y = − 4 by 2 to give 8 x − 2 y = − 8 We now have: 8 x − 2 y = − 8
5 z + 2 y = − 18 All we need to do now is ( 8 x − 2 y + 5 x + 2 y ) = ( − 18 − 8 ) ≡ 13 x = − 26 . Divide both sides by 13 to find x : 13 x = − 26
13 x 13 = − 26 13
x = − 2 Now put your value for x into either equation: 4 ( − 2 ) − y = − 4