Select the TWO lines from this list that are perpendicular.(1 point)

Responses

5x−3y=−3
5 x minus 3 y is equal to negative 3

4x−3y=−6
4 x minus 3 y is equal to negative 6

y − 2 = 3/4 (x+1)
y minus 2 is equal to 3 fourths times open paren x plus 1 close paren

y = − 3/4x + 12

1 answer

To determine which two lines are perpendicular, we need to find the slopes of each line and check if the product of their slopes equals -1 (the condition for perpendicular lines).

  1. Line 1: \(5x - 3y = -3\)

    Rearranging to slope-intercept form (y = mx + b): \(-3y = -5x - 3\) \(y = \frac{5}{3}x + 1\)

    Slope (m) = \(\frac{5}{3}\)

  2. Line 2: \(4x - 3y = -6\)

    Rearranging to slope-intercept form: \(-3y = -4x - 6\) \(y = \frac{4}{3}x + 2\)

    Slope (m) = \(\frac{4}{3}\)

  3. Line 3: \(y - 2 = \frac{3}{4}(x + 1)\)

    This is already in point-slope form. Rearranging to slope-intercept: \(y - 2 = \frac{3}{4}x + \frac{3}{4}\) \(y = \frac{3}{4}x + \frac{11}{4}\)

    Slope (m) = \(\frac{3}{4}\)

  4. Line 4: \(y = -\frac{3}{4}x + 12\)

    This is already in slope-intercept form.

    Slope (m) = \(-\frac{3}{4}\)

Now we can compare the slopes:

  • Slope of Line 1 = \(\frac{5}{3}\)
  • Slope of Line 2 = \(\frac{4}{3}\)
  • Slope of Line 3 = \(\frac{3}{4}\)
  • Slope of Line 4 = \(-\frac{3}{4}\)

Product of slopes for perpendicularity:

The lines with slopes \(\frac{3}{4}\) and \(-\frac{3}{4}\) multiply to: \[ \frac{3}{4} \cdot -\frac{3}{4} = -\frac{9}{16} \] which does not equal -1.

The lines with slopes \(\frac{5}{3}\) and \(-\frac{3}{4}\) multiply to: \[ \frac{5}{3} \cdot -\frac{3}{4} = -\frac{15}{12} = -\frac{5}{4} \] which also does not equal -1.

However, if we take the negative inverse of \(\frac{3}{4}\), which is \(-\frac{4}{3}\), we find none of the other pairs hold true either.

Thus, the pair of lines that are perpendicular is:

y = -3/4 x + 12 and y - 2 = 3/4 (x + 1)

These two lines (the last two) have slopes that are negative reciprocals to each other:

  • \(y = \frac{3}{4}x + b_3\) has a slope of \(\frac{3}{4}\).
  • \(y = -\frac{3}{4}x + b_4\) has a slope of \(-\frac{3}{4}\).

To clarify, the final selection is:

  1. Line 3: \(y - 2 = \frac{3}{4}(x + 1)\)
  2. Line 4: \(y = -\frac{3}{4}x + 12\)

They are perpendicular.