2. Solving Systems of Linear Equations by Substitution
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After isolating y in both equations, which expression is shorter?
Equation to Be Manipulated: 3x-y=0
Variable to Be Isolated: y
Which variable in which equation would be the easiest to isolate? Well, the coefficient of y in the equations is 1 or -1, which makes it easy to isolate y. 3x=y y= -2x-10 If we rearrange the first equation, we get the following system. y= 3x y= -2x-10 We should also consider how difficult the substitution will become when we solve the system. The expression equal to y in (II) is more complicated than the expression equal to y in (I), so we should use (I) to solve for a variable.