Question

Equação : 5x² + 21x + 4 = 0 Qual O Calculo ?

Answer 1

delta=b²-4ac
delta=21²-4x5x4
delta=441-80 = 361= raiz de 19
ai faz bhaskara

Answer 2

$\large\boxed{\begin{array}{l} \rm \: 5x {}^{2} + 21x + 4 = 0 \\ \\ \rm \: \rightarrow \begin{cases} \rm \: a = 5 \\ \rm \: b = 21 \\ \rm \: c = 4\end{cases} \\ \\ \rm\Delta = b {}^{2} - 4ac \\ \Delta = 21 {}^{2} - 4 \: . \: 5 \: .4 \\ \Delta = 441 - 80 \\\Delta = 361 \\ \\ \rm \: x = \dfrac{ - b \pm \sqrt{\Delta} }{2a} \\ \\ \rm \: x = \dfrac{ - 21 \pm \sqrt{361} }{2 \: . \: 5} \\ \\ \rm \: x = \dfrac{ - 21 \pm19 }{10} \begin{cases} \rm \: x_1 = \dfrac{ - 21 + 19}{10} = \dfrac{ - 2}{10} = \dfrac{ - 1}{5} \\ \\ \rm \: x_2 = \dfrac{ - 21 - 19}{10} = \dfrac{ - 40}{10} = - 4 \end{cases}\end{array}}$