Question

Me ajudem ai.. EM Qual DOS ITENS A SEGUIR ESTÃO INDICADAS AS RAÍZES DA EQUAÇÃO 2X ELEVADO A 2 +5X-3=0.

Answer 1

$2x^2+5x-3=0~~~\Rightarrow~~\left\{ \!\begin{array}{l} a=2\\b=5\\c=-3 \end{array} \right.\\\\\\ \Delta=b^2-4ac\\\\ \Delta=5^2-4\cdot 2\cdot (-3)\\\\ \Delta=25+24\\\\ \Delta=49=7^2$

$x=\dfrac{-b\pm \sqrt{\Delta}}{2a}\\\\\\ x=\dfrac{-5\pm \sqrt{7^2}}{2\cdot 2}\\\\\\ x=\dfrac{-5\pm 7}{4}\\\\\\ \begin{array}{rcl} x=\dfrac{-5+7}{4}&~\text{ ou }~&x=\dfrac{-5-7}{4}\\\\ x=\dfrac{2}{4}&~\text{ ou }~&x=\dfrac{-12}{4}\\\\ x=\dfrac{1}{2}&~\text{ ou }~&x=-3 \end{array}$


Resposta: alternativa $\text{b) }-3\text{ e }\dfrac{1}{2}.$