Question

(X-3)(x+3)=12-(x-2)(x+2 urgent sunt in timpul testului pls

Answer 1

$(x - 3)(x + 3) = 12 - (x - 2)(x + 2)$

${x}^{2} - {3}^{2} = 12 - ( {x}^{2} - {2}^{2} )$

${x}^{2} - 9 = 12 - ( {x}^{2} - 4)$

${x}^{2} - 9 = 12 - {x}^{2} + 4$

${x}^{2} + {x}^{2} = 12 + 4 + 9$

$2 {x}^{2} = 25$

${x}^{2} = \frac{25}{2}$

$x = \pm \sqrt{ \frac{25}{2} }$

$x = \pm \frac{ \sqrt{25} }{ \sqrt{2} }$

$x = \pm \frac{5}{ \sqrt{2} }$

$x = \pm \frac{5 \sqrt{2} }{2}$

Answer 2

(X-3)(x+3)=12-(x-2)(x+2)

=> x² - 9 = 12 - (x² - 4)

     x² - 9 = 12 - x² + 4

    2x² = 12+4+9

    2x² = 25 

      x= √(25/2)  ⇒  x₁ = 5√2/2   si    x₂ = - 5√2/2