Question

Номер 278, б,в,д.........................................................................................................................,,,,,.................

Answer 1

$y^4-6y^2+8=0 \ y^2=a geq 0 \ a^2-6a+8=0 \ D_1=(-3)^2-1cdot8=1 \ a=3+1=4Rightarrow y^2=4; y=pm2 \ a=3-1=2Rightarrow y^2=2; y=pm sqrt{2}$

$t^4-10t^2+25=0 \ (t^2)^2-2cdot t^2cdot5+5^2=0 \ (t^2-5)^2=0 \ t^2-5=0 \ t^2=5 \ t=pm sqrt{5}$

$9x^4-9x^2+2=0 \ x^2=a geq 0 \ 9a^2-9a+2=0 \ D=(-9)^2-4cdot9cdot2=81-72=9 \ a= frac{9+3}{18} =frac{2}{3} Rightarrow x^2=frac{2}{3} ; x=pm sqrt{frac{2}{3}} =pm frac{ sqrt{6} }{3} \ a= frac{9-3}{18} =frac{1}{3} Rightarrow x^2=frac{1}{3} ; x=pm sqrt{frac{1}{3}} =pm frac{ sqrt{3} }{3}$

Answer 2

Спасибо