Question

Cho biểu thức \(x^6-2x^4+1\). Biết \(x^2=5\). Khi đó A =

Answer 1

Ta có

\(A=\left(x^2\right)^3-2\left(x^2\right)^2+1\)

Với x²=5

=> \(A=5^3-2.5^2+1\)

=> \(A=125-50+1\)

=> \(A=76\)

Answer 2

A=x⁶-2x⁴+1

=(x²)³-2(x²)²+1

Tại x²=5 thì A=5³-2*5²+1

=125-50+1=76

 

Answer 3

\(A=x^6-2x^4+1\)

\(\Rightarrow A=x^2.x^2.x^2-2x^2.x^2+1\)

Thay \(x^2=5\) ta có:

\(A=5.5.5-2.5.5+1\)

\(\Rightarrow A=125-50+1\)

\(\Rightarrow A=76\)

Vậy \(A=76\)

Answer 4

$A=x^6-2x^4+1$

\(\Rightarrow A=\left(x^2\right)^3-2\left(x^2\right)^2+1\)

Khi \(x^2=5\Rightarrow A=5^3-2.5^2+1\)

\(\Rightarrow A=125-50+1\)

\(\Rightarrow A=76\)

Vậy \(A=76\)