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User Taro Sato
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The pair of lines that are perpendicular is D) \(x + y = 10; x - y = 3\).

Lines are perpendicular if the product of their slopes is -1. The slope of a line in the form \(y = mx + b\) is \(m\).

Let's check each pair of lines:

A) Line 1: \(8x - 4y = 24\)

Rearrange to slope-intercept form: \(-4y = -8x + 24 \implies y = 2x - 6\)

Slope of Line 1: \(m_1 = 2\)

Line 2: \(y = -2x + 7\)

Slope of Line 2: \(m_2 = -2\)

\(m_1 \times m_2 = 2 \times (-2) = -4\)

The slopes are not negative reciprocals, so Lines A are not perpendicular.

B) Line 3: \(x - 3y = 15\)

Rearrange to slope-intercept form: \(-3y = -x + 15 \implies y = \frac{1}{3}x - 5\)

Slope of Line 3: \(m_3 = \frac{1}{3}\)

Line 4: \(y = 3x + 4\)

Slope of Line 4: \(m_4 = 3\)

\(m_3 \times m_4 = \frac{1}{3} \times 3 = 1\)

The slopes are not negative reciprocals, so Lines B are not perpendicular.

C) Line 5: \(2x - 5y = 5\)

Rearrange to slope-intercept form: \(-5y = -2x + 5 \implies y = \frac{2}{5}x - 1\)

Slope of Line 5: \(m_5 = \frac{2}{5}\)

Line 6: \(5x - 2y = 4\)

Rearrange to slope-intercept form: \(-2y = -5x + 4 \implies y = \frac{5}{2}x - 2\)

Slope of Line 6: \(m_6 = \frac{5}{2}\)

\(m_5 \times m_6 = \frac{2}{5} \times \frac{5}{2} = 1\)

The slopes are not negative reciprocals, so Lines C are not perpendicular.

D) Line 7: \(x + y = 10\)

Rearrange to slope-intercept form: \(y = -x + 10\)

Slope of Line 7: \(m_7 = -1\)

Line 8: \(x - y = 3\)

Rearrange to slope-intercept form: \(y = x - 3\)

Slope of Line 8: \(m_8 = 1\)

\(m_7 \times m_8 = -1 \times 1 = -1\)

The slopes are negative reciprocals, so Lines D are perpendicular.

E) Line 9: \(5x - y = 1\)

Rearrange to slope-intercept form: \(-y = -5x + 1 \implies y = 5x - 1\)

Slope of Line 9: \(m_9 = 5\)

Line 10: \(y = \frac{1}{5}x + 9\)

Slope of Line 10: \(m_{10} = \frac{1}{5}\)

\(m_9 \times m_{10} = 5 \times \frac{1}{5} = 1\)

The slopes are not negative reciprocals, so Lines E are not perpendicular.

The pair of lines that are perpendicular is D) \(x + y = 10; x - y = 3\).

User Christian Kolb
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