2. Solving Systems of Linear Equations by Substitution
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After isolating x in both equations, which expression is shorter?
Equation to Be Manipulated: x-y=-3
Variable to Be Isolated: x
x-y=-3 & (I) 4x+3y=-5 & (II) Which variable in which equation would be the easiest to isolate? Well, the coefficient of x in the first equation is 1, which makes it easy to isolate x. x= y-3 & (I) 4x+3y=-5 & (II) We could have chosen to isolate x in the second equation. However, in the second equation, the coefficient of x is 4 and the constant is - 5. The fact that we have easier, smaller numbers in the first equation makes this the best candidate.