Question

Giúp mình với

Answer 1

Có: $A(x)=x^5-5x^4+5x^3-5x^2+5x-1$

$\Rightarrow A(4)=4^5-5\cdot4^4+5\cdot4^3-5\cdot4^2+5\cdot4-1$

$=4^5-(4+1)\cdot4^4+(4+1)\cdot4^3-(4+1)\cdot4^2+(4+1)\cdot4-1$

$=4^5-4^5-4^4+4^4+4^3-4^3-4^2+4^2+4-1$

$=3$

Vậy $A(4)=3$.