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Zorluk: OrtaSolving Systems of Linear Equations

If (x,y)(x, y) is the solution to the system of equations below, what is the value of the expression x+3yx + 3y?

3x−2y=143x - 2y = 14
x=y+5x = y + 5
  1. A
    21
  2. B
    -9
  3. 1Cevap
  4. D
    41

Cevap

The value of the expression is 1.
The system can be efficiently solved using substitution because the second equation already isolates xx. Substituting x=y+5x = y + 5 into the first equation yields 3(y+5)−2y=143(y + 5) - 2y = 14. Distributing the 33 gives 3y+15−2y=143y + 15 - 2y = 14, which simplifies to y=−1y = -1. Substituting this back into the second equation gives x=−1+5=4x = -1 + 5 = 4. Finally, the question asks for the value of x+3yx + 3y, which evaluates to 4+3(−1)=14 + 3(-1) = 1.

Adım Adım Çözüm

1
Substitute the expression for xx from the second equation into the first equation.
3(y+5)−2y=143(y + 5) - 2y = 14
This isolates a single variable, allowing us to solve for yy.
2
Distribute the 3 and solve the resulting equation for yy.
3y+15−2y=14⇒y+15=14⇒y=−13y + 15 - 2y = 14 \Rightarrow y + 15 = 14 \Rightarrow y = -1
Expanding the terms allows combining like terms to find the value of yy.
3
Substitute y=−1y = -1 back into the second equation to determine xx.
x=−1+5⇒x=4x = -1 + 5 \Rightarrow x = 4
Both values are needed for the final expression.
4
Evaluate the target expression x+3yx + 3y using the values found for xx and yy.
4+3(−1)=4−3=14 + 3(-1) = 4 - 3 = 1
The question specifically asks for the evaluated value of this expression, not just the ordered pair.

Anahtar Kavram

Solving a system of linear equations using the substitution method and evaluating an algebraic expression.
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