a)x⁴-7x³+6x²=0 x²(x²-7x+6)=0 Δ=49-24 Δ=25 x₁=7-52=1 x₂=7+52=6 b)x⁴-x²-12=0 x²=t x⁴=t² t²-t-12=0 Δ=1+48 Δ=49 t₁= 1-72=-3 t₂=4 x²=4 (x²-4)=0 (x-2)(x+2)=0 x=2 x=-2 x²=-3 --> brak pierwiastka c)x⁴+2x²-3=0 x²=t x⁴=t² t²+2t-3=0 Δ= 4+12 Δ=16 t₁= -2-42= -3 t₂= 1 x²=1 (x²-1)=0 (x-1)(x+1)=0 x=1 x=-1 x²=-3 --> brak pierwiastka d)x⁴+6x³-7x²=0 x²(x²+6x-7)=0 Δ=36+28 Δ=64 x₁= -6-82= -7 x₂= -6+82=1 e)x³+8x²-9x=0 x(x²+8x-9)=0 Δ=64+36 Δ=100 x₁= -8-102= -9 x₂= -8+102=1 f)x⁴-15x²-16=0 x²=t x⁴=t² 4t²-15t-16=0 Δ= 225+64 Δ=289 t₁= 15-172= -1 t₂=15+172= 16 x²=16 (x²-16)=0 (x-4)(x+4)=0 x=4 x=-4 x²=-1 --> brak pierwiastka g)x⁴-20x³+19x²=0 x²(x²-20x+19)=0 Δ=400-76 Δ=324 x₁= 20-182=1 x₂=20+182=19 h)x⁴-7x²-18=0 x²=t x⁴=t² t²-7t-18=0 Δ= 49+72 Δ=121 t₁= 7-112= -2 t₂=7+112= 9 x²=9 (x²-9)=0 (x-3)(x+3)=0 x=3 x=-3 x²=-2 --> brak pierwiastka
W załącznikach. Ale nie wiem czy dobrze.