Question

решите квадратное уравнение 7х^2-2х-9=0​

Answer 1

$7x^{2}-2x-9=0;\\D = 4 + 252 = 256;\\x_{1}=\frac{2+16}{14}=\frac{18}{14}=\frac{9}{7};\\x_{2}=\frac{2-16}{14}=-1.$

Answer 2

7х^2 - 2х - 9 = 0

D = b^2 - 4ac = 4 + 252 = 256
x1,2 = -b +- кореньD / 2a

x1 = 2 - 16 / 14 = -14 / 14 = -1

x2 = 2 + 16 / 14 = 18 / 14 = 9/7