Question

9 + 7x = 7x²
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Answer 1

Resposta:

Explicação passo a passo:

9 + 7x = 7x²

0 = 7x² -7x - 9    ou   7x² -7x - 9 = 0

a = 7

b = -7

c = -9

$\Delta = b^2-4.a.c\\\\\Delta =(-7)^2-4*7*(-9)\\\\\Delta = 49+252\\\\\Delta =301$

Raízes

$x'=\frac{-b+\sqrt{\Delta} }{2a} =\frac{7+\sqrt{301} }{2*7}\\\\x'=\frac{7+\sqrt{301} }{14}$

ou

$x''=\frac{-b-\sqrt{\Delta} }{2a} =\frac{7-\sqrt{301} }{2*7}\\\\x''=\frac{7-\sqrt{301} }{14}$