Question

Здравствуйте, помогите пожалуйста! Восьмой класс!!

Answer 1

$frac{1}{ x_{1} ^{2}}+ frac{1}{x _{2} ^{2}} = frac{x _{1} ^{2} +x _{2} ^{2}}{(x _{1}* x_{2}) ^{2} }= frac{( x_{1} + x_{2}) ^{2} -2 x_{1} x_{2} }{( x_{1} x_{2} ) ^{2} } = frac{2,5 ^{2}-2*(-2) }{(-2) ^{2} } = frac{6,25+4}{4} =2,5625\\ x_{1} x_{2} ^{4}+ x_{2} x_{1} ^{4}= x_{1} x_{2}( x_{2} ^{3} + x_{1} ^{3})= x_{1} x_{2}( x_{1}+ x_{2})( x_{1} ^{2}- x_{1} x_{2}+ x_{2} ^{2})=$$- 2*2,5*(10,25+2)=-5*12,25=-61,25$

Answer 2

2x²⁻5x-4=0
x²-2,5x-2=0


1)
1/x₁²+1/x₂²=(x₁²+x₂²)/x₁²*x₂²=((x₁²+2*x₁*x₂+x₂²)-2*x₁*x₂)/(x₁*x₂)²=((x₁+x₂)²-2*x₁*x₂)/(x₁*x₂)²=(2,5²+4)/4²=10,25/16=41/64


2)
x₁*x₂⁴+x₂*x₁⁴=x₁*x₂(x₁³+x₂³)=x₁*x₂*(x₁+x₂)*(x₁²-x₁*x₂+x₂²)=x₁*x₂*(x₁+x₂)*(x₁²+2*x₁*x₂+x₂²-3*x₁*x₂)=x₁*x₂*(x₁+x₂)*((x₁+x₂)²-3*x₁*x₂)=-2*2,5*(6,25+6)=-5*12,25=-61,25

Answer 3

В первом ошибка.

Answer 4

Все равно, спасибо огромное!

Answer 5

Правильное решение: 1/x₁²+1/x₂²=(x₁²+x₂²)/x₁²*x₂²=((x₁²+2*x₁*x₂+x₂²)-2*x₁*x₂)/(x₁*x₂)²=((x₁+x₂)²-2*x₁*x₂)/(x₁*x₂)²=(2,5²+4)/4=10,25/4=2,5625

Answer 6

первого