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Question

Tính $A=x^5-2018x^4+2018x^3-2018x^2+2018x-1000$ tại x=2017

Akai Haruma · Accepted Answer

Lời giải:

Ta có:

$A=x^5-2018x^4+2018x^3-2018x^2+2018x-1000$

$A=(x^5-2017x^4)-(x^4-2017x^3)+(x^3-2017x^2)-(x^2-2017x)+x-1000$

$A=x^4(x-2017)-x^3(x-2017)+x^2(x-2017)-x(x-2017)+x-1000$

Tại $x=2017\Rightarrow A=2017^4.0-2017^3.0+2017^2.0-2017.0+2017-1000$

$A=2017-1000=1017$Câu trả lời: Lời giải:

Ta có:

$A=x^5-2018x^4+2018x^3-2018x^2+2018x-1000$

$A=(x^5-2017x^4)-(x^4-2017x^3)+(x^3-2017x^2)-(x^2-2017x)+x-1000$

$A=x^4(x-2017)-x^3(x-2017)+x^2(x-2017)-x(x-2017)+x-1000$

Tại $x=2017\Rightarrow A=2017^4.0-2017^3.0+2017^2.0-2017.0+2017-1000$

$A=2017-1000=1017$

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