Question

Difficulty: EasySystems of Linear Equations

A system of two linear equations is given below.

y=x2y = x - 2
2x3y=12x - 3y = 1

If (x,y)(x, y) is the solution to the system of equations, what is the value of xx?

  1. 5Answer
  2. B
    -7
  3. C
    -5
  4. D
    7

Answer

The value of xx is 5.
To find the value of xx, substitute the expression for yy from the first equation into the second equation: 2x3(x2)=12x - 3(x - 2) = 1. Distribute the 3-3 to obtain 2x3x+6=12x - 3x + 6 = 1, which simplifies to x+6=1-x + 6 = 1. Subtracting 6 from both sides gives x=5-x = -5. Multiplying or dividing both sides by 1-1 yields x=5x = 5.

Step-by-Step Solution

1
Substitute the expression for yy from the first equation into the second equation.
2x3(x2)=12x - 3(x - 2) = 1
Substituting the expression reduces the system of two equations to one linear equation containing only the variable xx.
2
Distribute the coefficient 3-3 to both terms inside the parentheses.
2x3x+6=12x - 3x + 6 = 1
Applying the distributive property removes the parentheses so that like terms can be combined.
3
Combine like terms and isolate xx.
x+6=1    x=5    x=5-x + 6 = 1 \implies -x = -5 \implies x = 5
Combining the xx terms and subtracting 6 from both sides isolates x-x, allowing you to find the final value of xx.

Key Concept

Solving systems of linear equations using the substitution method

Alternative Method

Alternatively, you can solve this system using elimination. First, rewrite the first equation in standard form by subtracting xx from both sides, which gives x+y=2-x + y = -2. Next, multiply this equation by 3 to align coefficients: 3x+3y=6-3x + 3y = -6. Adding this result directly to the second equation, 2x3y=12x - 3y = 1, eliminates the yy terms and leaves x=5-x = -5, which simplifies to x=5x = 5.
Estimated Time:45s
Rate this question