STRAIGHT LINE - PARALLEL

Example 

Given that the straight line l passing through point P(-2, 5) and parallel with 2y - 4x = 10.  Find the straight line l.  
(Diberi garis lurus l melalui titik P(-2, 5) dan selari dengan 2y - 4x = 10.  Cari garis lurus l.)

Tip : Straight line y = mx + c, find m and c.

Solution:

Step 1 (Langkah 1) : Find m.

Convert 2y - 4x = 10 to y = mx + c
(Tukarkan 2y - 4x = 10 ke y = mx + c)

2y - 4x = 10
2y = 4x + 10
y = 2x + 5 -----------both sides divided by 2 (kedua-dua bahagian persamaan dibahagi 2)
Compare / Bandingkan
y = 2x + 5 with y = mx + c
Because they are parallel, both lines have the same gradient , so m = 2 
(Kerana kedua-dua garis adalah selari,  kecerunan kedua-dua garis adalah sama, maka m = 2)

Step 2 (Langkah 2): Find c

y = 2x + c
To find c, use P(-2, 5) that is x = -2, and y = 5
(Untuk mencari c, guna P(-2, 5), ii x = -2 dan y = 5)
5 = 2(-2) + c
5 = -4 + c
c = 5 + 4 = 9

Answer :

Straight line l :    y = 2x + 9