Question

-х^2+4х+3=0 решить через дискриминант

Answer 1

$-x^2+4x+3=0\\\\x^3-4x+3=0\\\\D=(-4)^2-4*1*(-3)=28\\\\x_1=\frac{4+\sqrt{28}}{2} =2+\sqrt{7} \\\\x_2=\frac{4-\sqrt{28}}{2} =2-\sqrt{7}\\\\\boxed {x_1=2+\sqrt{7}\;;\;x_2=2-\sqrt{7}}$