Question

помогите решить х2+17х+72=0

Answer 1

$<var>x^2+17x+72=0 \\ D=17^2-4*72=1 \\ \sqrt {D}= \sqrt {1} = 1 \\ x_{1}=\frac {-b+\sqrt D}{2a}=\frac {-17+1}{2}=\frac {-16}{2}=-8 \\ x_{2}=\frac {-b-\sqrt D}{2a}=\frac {-17-1}{2}=\frac {-18}{2}=-9</var>$