X² + 10 × 21 = 0
2 tentukan akar akar persamaan berikut menggunakan cara melengkapkan kuadrat sempurna
X² -2 × -8 =0
X² -4 × -32 = 0
Penjelasan dengan langkah-langkah:
no. 2
[tex] {x}^{2} - 2x - 8 = 0 \\ {x}^{2} - 2x = 8 \\ {x}^{2} - 2x + {( \frac{1}{2} \times 2 )}^{2} = 8 + {( \frac{1}{2} \times 2})^{2} \\ {x}^{2} - 2x + 1 = 8 + 1 \\ {x}^{2} - 2x + 1 = 9 \\ {(x - 1)}^{2} = 9 \\ x - 1 = \frac{ + }{ } \sqrt{9} \\ \\ x - 1 = \frac{ + }{?} 3 \\ x - 1 = 3 \\ x = 3 + 1 \\ x = 4 \\ \\ x - 1 = - 3 \\ x = - 3 + 1 \\ x = - 2[/tex]
[tex] {x}^{2} - 4x - 32 = 0 \\ {x}^{2} - 4x = 32 \\ {x}^{2} - 4x + {( \frac{1}{2} \times 4) }^{2} = 32 + {( \frac{1}{2} \times 4) }^{2} \\ {x}^{2} - 4x + 4 = 32 + 4 \\ {x}^{2} - 4x + 4 = 36 \\ {(x - 2)}^{2} = 36 \\ x - 2 = \sqrt{36} \\ x - 2 = \frac{ + }{} 6 \\ x - 2 = 6 \\ x = 6 + 2 \\ x = 8 \\ x - 2 = - 6 \\ x = - 6 + 2 \\ x = - 4[/tex]
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