Question

calcule : x² -4x-5=0.

Answer 1

Delta = b^2 - 4ac
Delta = 16 - 4 * 1 * - 5
Delta = 36

X1 = 4 + 6 /2 = 5
X2 = 4-6 /2 = - 1

Answer 2

Resposta:

$S=\{-1,5\}$

Explicação passo-a-passo:

$x^{2} -4x-5=0$

$a=1\\b=(-4)\\c=(-5)$

$\Delta=b^{2} -4ac\\\Delta=(-4)^{2}-4\times1\times(-5)\\\Delta=16+20\\\Delta=36$

$x=\frac{-b\pm\sqrt{\Delta} }{2a} \\\\x=\frac{-(-4)\pm\sqrt{36} }{2\times1} \\\\x=\frac{4\pm6 }{2}$

$x_{1} =\frac{4+6}{2} =\frac{10}{2} =5\\\\x_{2} =\frac{4-6}{2} =-\frac{2}{2} =-1$

$S=\{-1,5\}$