Which statement describes the graph of the system of equations below?

1.5x + 0.2y = 2.68

1.6x + 0.3y = 2.98

The lines are parallel.
The lines overlap at all points.
The lines intersect at (1.6,1.4).
The lines intersect at (3.1,0.5).

1 answer

To determine the relationship between the two lines represented by the given equations, we can analyze their slopes and intercepts.

  1. Find the slope of each equation in the slope-intercept form (y = mx + b):

For the first equation: \[ 1.5x + 0.2y = 2.68 \]

Rearranging this gives: \[ 0.2y = -1.5x + 2.68 \] \[ y = -7.5x + 13.4 \]

The slope (m) of the first line is -7.5.

For the second equation: \[ 1.6x + 0.3y = 2.98 \]

Rearranging this gives: \[ 0.3y = -1.6x + 2.98 \] \[ y = -\frac{16}{3}x + \frac{2.98}{0.3} \] Calculating the constant: \[ \frac{2.98}{0.3} \approx 9.9333 \] So, \[ y \approx -5.3333x + 9.9333 \]

The slope (m) of the second line is approximately -5.33.

  1. Compare the slopes: The slopes are different (-7.5 and -5.33), so the lines are not parallel.

  2. Check if there is a point of intersection: To find if they intersect, we can try solving the two equations together. We can set them equal to find the \(x\) and \(y\) values.

Solving the system of equations:

  1. \( 1.5x + 0.2y = 2.68 \) (Multiply by 10) → \( 15x + 2y = 26.8 \)
  2. \( 1.6x + 0.3y = 2.98 \) (Multiply by 10) → \( 16x + 3y = 29.8 \)

Now we can use the method of elimination or substitution, but instead, we'll use a quick numerical check:

  1. If we check the proposed intersection points:

    • For (1.6, 1.4):
      • First equation: \( 1.5(1.6) + 0.2(1.4) = 2.4 + 0.28 = 2.68 \) (True)
      • Second equation: \( 1.6(1.6) + 0.3(1.4) = 2.56 + 0.42 = 2.98 \) (True)
    • Therefore, they indeed intersect at (1.6, 1.4).
  2. Checking the second proposed point (3.1, 0.5):

    • First equation: \( 1.5(3.1) + 0.2(0.5) = 4.65 + 0.1 = 4.75\) (False)
    • This point does not satisfy the first equation.

So the valid conclusion is:

The lines intersect at (1.6, 1.4).

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