Matematika
Nomor 5
6x² - x - 1 = (3x + 1)(2x -1)
f(x) = ax + b
2x - 1 = 0
x = ½
f(½) = ½ a + b
3 = ½ a + b (kedua ruas ×2)
6 = a + 2b
3x + 1 = 0
x = - ⅓
f(-⅓) = -⅓ a + b
-7 = -⅓ a + b (kedua ruas ×3)
-21 = -a + 3b
Eliminasi
a + 2b = 6
-a + 3b = -21
_____________+
5b = -15
b = -3
Subtitusi
a + 2(-3) = 6
a = 6 + 6
a = 12
= 12x - 3
jawaban C
Jadi, sisanya 12x-3 (C).
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Matematika
Nomor 5
6x² - x - 1 = (3x + 1)(2x -1)
f(x) = ax + b
2x - 1 = 0
x = ½
f(½) = ½ a + b
3 = ½ a + b (kedua ruas ×2)
6 = a + 2b
3x + 1 = 0
x = - ⅓
f(-⅓) = -⅓ a + b
-7 = -⅓ a + b (kedua ruas ×3)
-21 = -a + 3b
Eliminasi
a + 2b = 6
-a + 3b = -21
_____________+
5b = -15
b = -3
Subtitusi
a + 2b = 6
a + 2(-3) = 6
a = 6 + 6
a = 12
f(x) = ax + b
= 12x - 3
jawaban C
Jadi, sisanya 12x-3 (C).