Jawaban:
1. x² - 6x + 8 = 0
x² - 6x = -8
x² - 6x + 3² = -8 + 3²
x² - 6x + 3² = -8 + 9
x² - 6x + 3² = 1
(x - 3)² = ± 1
[tex]x - 3= ± \sqrt{1} [/tex]
[tex]x - 3 = ±1[/tex]
[tex]x = ±1 + 3[/tex]
x1 = 1 + 3
x1 = 4
x2 = -1 + 3
x2 = 2
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2. x² + 9x + 20 = 0
[tex] {x}^{2} + 9x = - 20[/tex]
[tex] {x}^{2} + 9x + {( \frac{9}{2} })^{2} = - 20 + {( \frac{9}{2} })^{2} [/tex]
[tex] {x}^{2} + 9x + {( \frac{9}{2} })^{2} = 20 + \frac{81}{4} [/tex]
[tex] {(x + \frac{9}{2} })^{2} = \frac{ - 80}{4} + \frac{81}{4} [/tex]
[tex] {(x + \frac{9}{2} })^{2} = \frac{1}{4} [/tex]
[tex]x + \frac{9}{2} = ± \sqrt{ \frac{1}{4} } [/tex]
[tex]x + \frac{9}{2} = \frac{1}{2} [/tex]
[tex]x = ±\frac{1}{2} - \frac{9}{2} [/tex]
[tex]x1 = \frac{ 1}{2} - \frac{9}{2} [/tex]
[tex]x1 = \frac{ - 8}{2} = \bold{- 4}[/tex]
[tex]x2 = \frac{ - 1}{2} - \frac{9}{2} [/tex]
[tex]x2 = \frac{ - 10}{2} = \bold{ - 5}[/tex]
Penjelasan dengan langkah-langkah:
x2 - 6x + 8 = 0 Dijabarkan menjadi
( x - 2) ( x - 4 ) = 0
x - 2=0
X1= 2
X2 - 4=0
X2 = 4
maka diperoleh (X1,X2) adalah (2,4)
x2 + 9x + 20= 0
( x + 5) ( x +4)=0
x +5=0
x1= -5
x +4=0
x2= -4
maka diperoleh hasil dari X1 X2 adalah (-5,-4)
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