Срочно , кроме 5-ого . Спасибо

1. x⁴-65x+64=0Пусть  x²=t>0   ⇒t²-65t+64=0   D=3969t₁=64   x²=64   x₁=8    x₂=-8t₂=1     x²=1     x₃=1    x₄=-1.2. 3x²-5x-2≤03x²-5x-2=0   D=49x₁=-1/3     x₂=2   ⇒(x+1/3)(x-2)≤0-∞________+_______-1/3_______-_______2________+________+∞x∈[-1/3;2].3. x²+y²-13=0         x²+y²-13=0      x²+y²=13    xy-6=0  |×2         2xy-12=0         2xy=12Суммируем эти уравнения:x²+2xy+y²=25(x+y)²=25x+y=5                                                      x+y=-5y=5-x                                                       y=-5-xx(5-x)-6=0                                               x(-5-x)-6=05x-x²-6=0                                                -5x-x²-6=0x²-5x+6=0  D=1                                       x²+5x+6=0   D=1x₁=3        x₂=2                                     x₃=-3          x₄=-2y₁=2        y₂=3                                     y₃=-2          y₄=-3.