Question

(Brainliest for fastest right answer!!!) Which is correct?

Answer 1

Answer:

Step-by-step explanation:

ax² + bx + c = a(x - $x_{1}$)(x - $x_{2}$)

D = b² - 4ac

$x_{12}$ = ( - b ± √D ) / 2a

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Let x² = y , then y² + 8y - 9

Find the roots of equation y² + 8y - 9 = 0

D = 64 + 36 = 100 = 10²

$y_{1}$ = ( - 8 - 10) / 2 = - 9  

$y_{2}$ = ( - 8 + 10) / 2 = 1

y² + 8y - 9 = (y - 1)(y + 9) = (x² - 1)(x² + 9)

x² = 1 ⇒ $x_{12}$ = ± √1

$x^{4}$ + 8x² - 9 = (x - 1)(x + 1)(x² + 9)