Respuesta :

nktselepov

[tex] {20x}^{2} + 7x - 49 = 0 \\ D = {7}^{2} - 4 \times 20 \times ( - 49) = 3969 = {63}^{2} \\ x_1 = \dfrac{ - 7 + 63}{40} = 1.4 \\ x_2 = \dfrac{ - 7 - 63}{40} = - 1.75[/tex]