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X+y=5 7x+37=27 solve the system of equations: x=3; y=2 x=4; y=4 x=6;y=1 x=3; y=5

1 Answer

6 votes

Answer:

(a) (x, y) = (3, 2)

Explanation:

The correct answer to the given system of equations can be found by trying the offered choices.

The equations are ...

  • x + y = 5
  • 7x +3y = 27

Evaluating "solutions"

The first equation tells you the sum of the x and y values is 5. Here's what we get for a sum from the different answer choices:

A: 3 +2 = 5 . . . . a viable choice

B: 4 +4 = 8 . . . . doesn't work

C: 6 +1 = 7 . . . . doesn't work

D: 3 +5 = 8 . . . . doesn't work

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Checking (x, y) = (3, 2) in the other equation, we have ...

7(3) +3(2) = 21 +6 = 27 . . . . as required

The solution is x = 3; y = 2.

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Additional comment

Often, the easiest way to find the answer to a multiple-choice question is to see which answer works to solve the problem. It can sometimes be easier to check the answer than to develop it in the first place.

Substitution can work for this problem to find the correct y-value. (The answer choices differ by y-values, so knowing y tells the answer.)

7(5 -y) +3y = 27 . . . . substitute x=5-y

35 -4y = 27 . . . . . . simplify

8 = 4y . . . . . . . . . add 4y-27

2 = y . . . . . . . . . divide by 2. Matches the first answer choice.

X+y=5 7x+37=27 solve the system of equations: x=3; y=2 x=4; y=4 x=6;y=1 x=3; y=5-example-1
User Komal Gupta
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