<span><span>4x - y = -4</span> <span><span>-y = -4 - 4x (subtract 4x from each side) y = 4 + 4x (divide by -1) y = 4x + 4 (commutative property of addition to get the x-value in front).
Now we must plug what we have gotten y to equal into the other equation. If we try to plug what we have rearranged back into the original equation, we don't get anywhere.
2x - y = -7 2x - 1(4x + 4) = -7 (substitution) 2x - 4x - 4 = -7 (distributive property with -1) -2x - 4 = -7 (combine like terms) -2x = -3 (add 4 to each side) x = 3/2 (divide by -2).
You</span></span><span>2x-y=7 Y=2x+3</span><span> have just solved for x! We can now plug what we have found for x into either equation to get what y equals. (If this is truly a system of linear equations, then it will not matter which one we use.)
2(3/2) - y = -7 (substitution)
6/2 - y = -7 (multiplication) 3 - y = -7 (division) - y = -10 (subtraction) y = 10 (division)
You have just found y! As a point, the solution to this system is (3/2, 10) with the x-coordinate first and the y-coordinate second. If we plug x and y into both equations, we will find that they will make the equations true. This is how we check ourselves. Using both equations:
