Question

Как решить неравенство: x^4-13x^2+36<0

Answer 1

displaystyle x^4-13x^2+36=0\\x^2=t\\t^2-13t+36=0\\D=169-144=25=5^2\\t_{1.2}= frac{13pm 5}{2}\\t_1=4; t_2=9\\x^2=4; x=pm 2 \\x^2=9; x=pm 3