44

 PAGE: 354 SET: Exercises PROBLEM: 44

Substitution:

Given equations are,

----------(1)

------(2)

The first equation is already solved for y,

so,  substitute for y in the second equation.

(Second equation)

(Substitute  )

(Multiply: )

Apply division property of equality: If a = b then .

(Divide each side by 20)

(Cancel common terms)

(Divide: )

Substitute for x in either equation to find y.

(first equation)

(Substitute  )

(Multiply: )

The solution is .

Check the solution:

To check, Substitute   and in either equation.

(first equation)

(Substitute  and )

(Multiply: )

The solution  is true.

If the system have only one solution, such as .

If the system have only one solution, such as .

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