JAMB - Mathematics (2021 - No. 6)
find the value of p if the line which passes through (-1, -p) and (-2,2) is parallel to the line 2y+8x-17=0?
\(\frac{-2}{7}\)
\(\frac{7}{6}\)
\(\frac{-6}{7}\)
2
Explanation
Line: 2y+8x-17=0
recall y = mx + c
2y = -8x + 17
y = -4x + \(\frac{17}{2}\)
Slope m\(_1\) = 4
parallel lines: m\(_1\). m\(_2\) = -4
where Slope ( -4) = \(\frac{y_2 - y_1}{x_2 - x_1}\) at points (-1, -p) and (-2,2)
-4( \(x_2 - x_1\) ) = \(y_2 - y_1\)
-4 ( -2 - -1) = 2 - -p
p = 4 - 2 = 2
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