Question

2x^2+5x-7=0 помогите решить!!

Answer 1

D=25+56=81=9^2
x1=-5+9/4=1
x2=-5-9/4=-3.5

Answer 2

$D= b^{2} -4*a*c = 5^{2} +4*2*7=25+56=81$
$x_{1,2} = -b+- sqrt{D} /2a$
$x_{1} =-5+9/4 =1$
$x_{2} = -5-9/4 =-3.5$