(a²-9b²)(a²+9b²)(a^4+81b^4)*3^8*b^8=(a^4-81b^4)*(3b)^8=
=(a^8-(3b)^8)*(3b)^8=(3ab)^8-(3b)^16
7
a²-6a+9-5a²+6a=9-4a²
a=-1/2 9-4*(-1/2)²=9-4*1/4=9-1=8
9
3ac²/[(a-4c)(a+4c)*(a-4c)/ac=3c/(a+4c)
a=2,1;c=-0,4
3*(-0,4)/(2,1-1,6)=-1,2/0,5=-2,4
![x^4 - 5x^2 + 4 = 0 \\x^2=y,\ y \geq 0 \\y^2-5y+4=0 \\D=25-16=9=3^2 \\y_1= \frac{5+3}{2} =4 \\y_2= \frac{2}{2} =1 \\x^2=4 \\x=\pm 2 \\x^2=1 \\x=\pm 1](https://tex.z-dn.net/?f=+x%5E4+-+5x%5E2+%2B+4+%3D+0%0A%5C%5Cx%5E2%3Dy%2C%5C+y+%5Cgeq+0%0A%5C%5Cy%5E2-5y%2B4%3D0%0A%5C%5CD%3D25-16%3D9%3D3%5E2%0A%5C%5Cy_1%3D+%5Cfrac%7B5%2B3%7D%7B2%7D+%3D4%0A%5C%5Cy_2%3D+%5Cfrac%7B2%7D%7B2%7D+%3D1%0A%5C%5Cx%5E2%3D4%0A%5C%5Cx%3D%5Cpm+2%0A%5C%5Cx%5E2%3D1%0A%5C%5Cx%3D%5Cpm+1)
Ответ: x1=2; x2=-2; x3=1; x4=-1