Question

3ײ-21×+30=0

$\sqrt{81 = 9}$
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Answer 1

Resposta:

S= { 2 , 5 }

Explicação passo-a-passo:

3x² - 21x + 30 = 0 (÷3)

x² - 7x + 10 = 0

$x = \frac{ - b + - \sqrt{delta} }{2a}$

$x = \frac{ - b + - \sqrt{ {b}^{2} - 4ac } }{2a}$

$x = \frac{ - ( - 7) + - \sqrt{ {( - 7)}^{2} - 4.1.10 } }{2.1}$

$x = \frac{7 + - \sqrt{49 - 40} }{2}$

$x = \frac{7 + - \sqrt{9} }{2}$

$x = \frac{7 + - 3}{2}$

$x1 = \frac{7 - 3}{2}$

$x1 = \frac{4}{2}$

x' = 2

$x2 = \frac{7 + 3}{2}$

$x 2= \frac{10}{2}$

x'' = 5

S = { 2 , 5 }

$\sqrt{81} = 9$

9 × 9 = 81