Question

If the line passing through (4, 3) and (2, k) is perpendicular to y = 2x + 3, then k=

• A. –1
• B. 1
• C. –4
• D. 4

Answer 1

Answer: (D)

4

Answer 2

Slope of line passes through (4, 3) and (2, k)

m₁ = $\frac{k - 3}{2 - 4}$= $\frac{k - 3}{- 2}$

slope of line y = 2x + 3 is m₂ = 2

lines are perpendicular

\ m₁m₂ = –1

Ž $\left( \frac{k - 3}{- 2} \right)$ (2) = – 1 Ž k = 4