Question

11.1
2) x4 – 8x2 - 9 = 0; – 0
4) 16x4 - 409x2 + 225 = 0.​

Answer 1

Ответ:

$x ^ { 4 } -8x ^ { 2 } -9=0 \\x ^ { 2 }=t\\ t ^ { 2 } -8t -9=0\\D=64-4*-9=100\\\sqrt{100}=10\\t1=\dfrac{8+10}{2} =9\\\\t2=\dfrac{8-10}{2}=-1\\\\x=-\sqrt{t} , x=+\sqrt{t} \\x=3\\x=-3\\\\16x^4 - 409x^2 + 225 = 0\\x ^ { 2 }=t\\16t^2 - 409t + 225 = 0\\\sqrt{D} =409^{2} -4*16*225=391\\t1=\dfrac{409+391}{32}=25\\t2=\dfrac{409-391}{32}=\dfrac{9}{16}\\\\x=5\\x=-5\\x=-\dfrac{3}{4}\\x=\dfrac{3}{4}$

Объяснение: