Rozwiąż a) 8 (x²-3)(x²+4)(x-7)=0 b) 3x³-15x² - 4x+20=0 c) x+1/x²-1=3

a) 8 (x²-3)(x²+4)(x-7)=0 |:8  (x²-3)(x²+4)(x-7)=0 x²-3=0 v x²+4=0 v x-7=0 x=[latex] sqrt{3} [/latex] v x=[latex]- sqrt{3} [/latex] v x=7 b) 3x³-15x² - 4x+20=0 3x²(x-5)-4(x-5)=0 (x-5)(3x²-4)=0 (x-5)([latex] sqrt{3} [/latex]x  -2)([latex] sqrt{3} [/latex] x +2) x=5 v x=[latex] frac{2 sqrt{3} }{3} [/latex] v x=[latex]- frac{2 sqrt{3} }{3} [/latex] c) [latex] frac{x+1}{ x^{2} -1} =3[/latex] [latex] frac{x+1}{(x-1)(x+1)} =3[/latex] [latex] frac{1}{x-1} =3[/latex] 3x-3=1 3x=4 [latex]x= frac{4}{3} [/latex]