Question Number 85555 by luxlavanish last updated on 22/Mar/20
$$\mathrm{2}{x}^{\mathrm{2}} +\mathrm{5}{x}+\mathrm{7}=\mathrm{0} \\ $$
Answered by MJS last updated on 23/Mar/20
$${ax}^{\mathrm{2}} +{bx}+{c}=\mathrm{0} \\ $$$$\Rightarrow \\ $$$${x}=\frac{−{b}\pm\sqrt{{b}^{\mathrm{2}} −\mathrm{4}{ac}}}{\mathrm{2}{a}} \\ $$$$\mathrm{in}\:\mathrm{this}\:\mathrm{case} \\ $$$${a}=\mathrm{2};\:{b}=\mathrm{5};\:{c}=\mathrm{7} \\ $$$${x}=\frac{−\mathrm{5}\pm\sqrt{\mathrm{5}^{\mathrm{2}} −\mathrm{4}×\mathrm{2}×\mathrm{7}}}{\mathrm{2}×\mathrm{2}}=\frac{−\mathrm{5}\pm\mathrm{i}\sqrt{\mathrm{31}}}{\mathrm{4}} \\ $$