Question

Sa se rezolve ecuatile a)x²=100,x€R.
b)y²=4supra9,y€Q

Answer 1

$\it x^2 = 100 \\ \\ x = \pm \sqrt{100} \\ \\ \boxed{\it x = \pm 10} \\ \\ \\ y^2 = \dfrac{4}{9} \\ \\ y = \pm \sqrt{ \dfrac{4}{9} } \\ \\ \boxed{y = \pm \it \dfrac{2}{3} }$

Answer 2

x² = 100

x² - 100 = 0

(x - 10)(x + 10) = 0

x - 10 = 0 => x1 = 10

x + 10 = 0 => x2 = -10


y² = 4/9

y² - 4/9 = 0

(y - 2/3)(y + 2/3) = 0

y - 2/3 = 0 => y = 2/3

y + 2/3 = 0 => y = -2/3

Obs. Am folosit formula de calcul prescurtat a² - b² = (a - b)(a + b)