tentukan nilai x yang memenuhi x²-7x-6=12
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Jawaban:
[tex]x = 9 \\ x = - 2[/tex]
Penjelasan dengan langkah-langkah:
Kita pakai penyelesaian kuadrat
[tex] {x}^{2} - 7x - 6 = 12 \\ {x}^{2} - 7x = 18 \\ {x}^{2} - 7x + ( - \frac{7}{2} ) {}^{2} = 18 + ( - \frac{7}{2} ) {}^{2} \\ {x}^{2} - 7x + ( - \frac{ 7}{2} ) {}^{2} = 18 + \frac{49}{4} \\ {x}^{2} - 7x + \frac{49}{4} = \frac{121}{4} \\ {(x - \frac{7}{2}) }^{2} = \frac{121}{4} \\ \sqrt{(x - \frac{7}{2} ) {}^{2} } = \sqrt{ \frac{121}{4} } [/tex]
Ada dua nilai x , niali yang pertama
[tex]x - \frac{7}{2} = \frac{11}{2} \\ x = \frac{11 + 7}{2} = \frac{18}{2} = 9[/tex]
Nilai x kedua
[tex]x - \frac{7}{2} = - \frac{11}{2} \\ x = - \frac{11 + 7}{2} = - \frac{4}{2} = - 2[/tex]
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