Find the value of a if the line 2y - ax + 4 = 0 is perpendicular to the line y + (x/4) - 7 = 0
Take Free Practice Test On 2026 JAMB UTME, Post UTME, WAEC SSCE, GCE, NECO SSCE
Correct Answer: Option C
Explanation:
2y - ax + 4 = 0 \(\implies\) 2y = ax - 4.
y + (x/4) - 7 = 0 \(\implies\) y = -x/4 + 7
 Slope of line 1 = a/2
Slope of line 2 = -1/4
-1/4 x a/2 = -1 (product of the slope of two perpendicular lines = -1)
a/8 = 1 \(\implies\) a = 8.
2y - ax + 4 = 0 \(\implies\) 2y = ax - 4.
y + (x/4) - 7 = 0 \(\implies\) y = -x/4 + 7
 Slope of line 1 = a/2
Slope of line 2 = -1/4
-1/4 x a/2 = -1 (product of the slope of two perpendicular lines = -1)
a/8 = 1 \(\implies\) a = 8.