You can
put this solution on YOUR website!The substitution method requires solving one equation for one variable in terms of the other, then substituting the derived expression for that variable into the second equation.
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Step 1: Solve one of the equations for x in terms of y, or y in terms of x. It doesn't matter which, though sometimes, because of the way the equation is presented, one may be easier than the other. In this case, your equation 1 is already solved for x in terms of y, and nothing could be easier than doing nothing, right?
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Step 2: Now that you have an expression for x in terms of y:
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you can substitute that expression in place of x in the other equation, thus:
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Step 3: Now that we know the value of y, we can substitute that value into either of the equations to obtain the value of x.
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Step 4: VERY IMPORTANT. Check your answer.
Does
? Yes! And,
Does
? Yes! So your answers check.
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Just to show you that it doesn't matter which variable you solve for or which equation you use in Step 1, let's do it another way and see if we get the same answers.
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Solving equation 2 for y:
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Substituting and solving:
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Substitute again and solve:
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And these are the same answers obtained before.
