Question

неравенства

1) 4-2x<9
2) x^2-4x-21>0
3) 1-16x^2>0

Answer 1

) 4-2x<9 => -2x<9-4 => x>2.5
2) x^2-4x-21>0 => D=(-4)^2-4*(-21)=16+84=100=10; x1 = (4+10)/2=7; x2=(4-10)/2=-3; Ответ: (-3;7)
3) 1-16x^2>0 => - 16x^2>-1 => 4x<1 => x< 0.25