9.3.7 Straight Lines, PT3 Focus Practice


Question 13:
Diagram shows a straight line ST and a straight line PQ drawn on a Cartesian plane.  ST is  parallel to PQ. Given that equation of the straight line ST is 2y = 8x + 3.
  


Find,
(a)  the equation of the straight line PQ,
(b)  the x-intercept of the straight line PQ.
[ 5 marks ]
Solution:
(a)
2 y = 8 x + 3 y = 4 x + 3 2  
m = 4
4 = 4 (6) + c 
c = 2
Using formula, y = mx + c   
equation of the straight line PQ is y = 4x 20. 

(b)
y = 4x 20, at x-intercept, y = 0
4x – 20 = 0,   y= 0
x = 5   or   x-intercept = 5

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