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Question

Tìm n thuộc N để mỗi phép chia sau là phép chia hết

a)$35x^9y^n:\left(-7x^7y^2\right)$

b)$\left(5x^3-7x^2+x\right):3x^n$

c)$\left(13x^4y^3-5x^3y^3+6x^2y^2\right):5x^ny^n$

Nguyễn Đức Trí · Accepted Answer

a) $35x^9y^n=5.\left(7x^9y^n\right)$

Để $35x^9y^n⋮\left(-7x^7y^2\right)$

$\Rightarrow n\in\left\{0;1;2\right\}$Câu trả lời: a) $35x^9y^n=5.\left(7x^9y^n\right)$

Để $35x^9y^n⋮\left(-7x^7y^2\right)$

$\Rightarrow n\in\left\{0;1;2\right\}$

Nguyễn Đức Trí · Answer

b) $5x^3-7x^2+x=3x\left(\dfrac{5}{3}x^2-\dfrac{7}{3}x+\dfrac{1}{3}\right)$

Để $\left(5x^3-7x^2+x\right)⋮3x^n$

$\Rightarrow3x\left(\dfrac{5}{3}x^2-\dfrac{7}{3}x+\dfrac{1}{3}\right)⋮3x^n$

$\Rightarrow n\in\left\{0;1\right\}$Câu trả lời: b) $5x^3-7x^2+x=3x\left(\dfrac{5}{3}x^2-\dfrac{7}{3}x+\dfrac{1}{3}\right)$

Để $\left(5x^3-7x^2+x\right)⋮3x^n$

$\Rightarrow3x\left(\dfrac{5}{3}x^2-\dfrac{7}{3}x+\dfrac{1}{3}\right)⋮3x^n$

$\Rightarrow n\in\left\{0;1\right\}$