Question

quais são as raizes da equação x²-3x-4=0

Answer 1

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$x^{2} -3x-4=0 \\ \\ a=1 \\ b=-3 \\ c=-4 \\ \\ \Delta=b^2-4ac \\ \Delta=(-3)^2-4(1)(-4) \\ \Delta=9+16 \\ \Delta=25$

$x=- \frac{b\pm \sqrt{\Delta} }{2a} = \frac{3\pm5}{2} \\ \\ x'= \frac{3+5}{2} = \frac{8}{2} =4 \\ \\ x"= \frac{3-5}{2} =- \frac{2}{2} =-1 \\ \\ \\ S=\{-1,4\}$

Answer 2

Resposta:

S = {- 1, 4}

Explicação passo-a-passo:

$x^{2} -3x-4=0$

$a=1\\b=(-3)\\c=(-4)$

$\Delta=b^{2} -4ac\\\Delta=(-3)^{2} -4\times1\times(-4)\\\Delta=9+16\\\Delta=25$

$x=\frac{-b\pm\sqrt{\Delta} }{2a} \\\\x=\frac{-(-3)\pm\sqrt{25} }{2\times1} \\\\x=\frac{3\pm5}{2}$

$x_{1} =\frac{3+5}{2} =\frac{8}{2} =4\\\\x_{2} =\frac{3-5}{2} =-\frac{2}{2} =-1$