Home / Assignment Help / Consider the following pair of equations: y = –2x + 8 y = x – 1 Explain how you will solve the pair of equations by substitution. Show all the steps and write the solution in (x, y) form. (5 points)

Consider the following pair of equations: y = –2x + 8 y = x – 1 Explain how you will solve the pair of equations by substitution. Show all the steps and write the solution in (x, y) form. (5 points)

There is a special kind of substitution which some books call it by comparison.

When the two equations are both 
y=some function of x
y=some other function of x, then
we can substitute the second equation into the first giving
some function of x = some other function of x and start solving.

For example,
y = –2x + 8 
y = x – 1
substitute second into first
x-1=-2x+8
isolate x on left,
3x=9
x=3
second step is to substitute x=3 into second equation to get
y=x-1=3-1=2
Therefore the solution is (3,2)

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