Question

решите неравенство 1420-x-x^2>=1

Answer 1

$1420-x-x^2geq 1\\0geq 1-1420+x+x^2\\x^2+x-1419leq 0\\D=1+4cdot 1419=5677\\x_1=frac{-1-sqrt{5677}}{2}approx -38,2; ,; ; x_2=frac{-1+sqrt{5677}}{2}approx 37 ,2\\znaki:; ; ; +++[, x_1, ]---[, x_2, ]+++qquad x_1leq xleq x_2\\Otvet:; ; xin [, frac{-1-sqrt{5677}}{2}; ;; frac{-1+sqrt{5677}}{2}; ]; .$