6.4.4 Persamaan Linear, Praktis Berformat PT3
Soalan 10:
Diberi bahawa 2x = 6 dan 3x + y = 10.
Hitung nilai y.
Penyelesaian:
2x = 6
x = 3
Gantikan x = 3 ke dalam 3x + y = 10
3 (3) + y = 10
y = 10 – 9
y = 1
Soalan 11:
Diberi bahawa y = –1 dan x – 3y = –10.
Hitung nilai x.
Penyelesaian:
Gantikan y = –1 ke dalam x – 3y = –10
x – 3 (–1) = –10
x + 3 = –10
x = –10 – 3
x = –13
Soalan 12:
Diberi bahawa 7x – 2y = 19 dan x + y = 13.
Hitung nilai y.
Penyelesaian:
Kaedah Penggantian
7x – 2y = 19 ——– (1)
x + y = 13 ——- (2)
Daripada persamaan (2),
x = 13 – y ——- (3)
Gantikan persamaan (3) ke dalam persamaan (1),
7x – 2y = 19
7 (13 – y) – 2y = 19
91 – 7y – 2y = 19
– 9y = 19 – 91
– 9y = –72
y = 8
Soalan 13:
Diberi bahawa 2x – y = 5 dan 3x – 2y = 8.
Hitung nilai x.
Penyelesaian:
Kaedah Penghapusan
2x – y = 5 ——– (1)
3x – 2y = 8 ——- (2)
(1) × 2: 4x – 2y = 10 -------- (3)
3x – 2y = 8 ------- (2)
(3) – (2): x – 0 = 2
x = 2
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