Question

алгебра помогите плез

Answer 1

$2x^2-5x-4=0; ; Rightarrow ; ; left { {{x_1+x_2=frac{5}{2}} atop {x_1cdot x_2=-frac{4}{2}}} right. ; ; left { {{x_1+x_2=2,5} atop {x_1cdot x_2=-2}} right.; left { {{(x_1+x_2)^2=6,25} atop {x_1cdot x_2=-2}} right. \\left { {{x_1^2+x_2^2+2x_1x_2=6,25} atop {x_1cdot x_2=-2}} right. ; left { {{x_1^2+x_2^2=6,25-2cdot (-2)} atop {x_1cdot x_2=-2}} right. ; left { {{x_1^2+x_2^2=10,25} atop {x_1cdot x_2=-2}} right. \\1); ; frac{1}{x_1^2}+frac{1}{x_2^2}=frac{x_1^2+x_2^2}{x_1^2cdot x_2^2}=frac{10,25}{(-2)^2}=frac{10,25}{4}=2,5625$

$2); ; x_1x_2^4+x_2x_1^4=x_1x_2cdot (x_2^3+x_1^3)=\\=x_1x_2cdot (x_1+x_2)cdot (x_1^2-x_1x_2+x_2^2)=-2cdot 2,5cdot Big (10,25-(-2)Big )=\\=-5cdot 12,25=-61,25$