Question 578
since you have two variables (x and y), you need two equations so that you can substitute in order to find each.
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step 1: set to linear format <b>y = mx + b</b>
1st equation: <i>y = -4x - 1</i>
2nd equation: <i>-y = 5x + 0</i> and we will need to get rid of the negative sign so multiply the whole equation by a negative. we do not need to write the zero so we will leave it out.
<i>- (-y = 5x) --> y = -5x</i>
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step 2: substitute your y from your 2nd equation (y=-5x) into the y of your 1st equation (y=-4x-1):
<i>-5x = -4x - 1</i>
*notice how there are no more y's in your equation and we combined your two equations into one equation.
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step 3: bring the x's to one side and your constants to the other.
-5x = -4x - 1
-5x + 4x = -1
-1x = -1
-1x/-1 = -1/-1
<b>x = 1</b>
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step 4: subsitute your x into your original equations. we will use the 1st one:
4x + y = -1
*remember we found that x = 1
4(1) + y = -1
y = -1 - 4
<b>y = -5</b>
step 5: check your work by substituting your x value and y value into the original equation.
4x + y = -1
*remember <b>x=1</b> and <b>y=-5</b>
4(1) +  (-5) = -1
4 - 5 = -1 and your answer checks out therefore the values of your x and y are correct.