Câu hỏi của Trần Lê Minh

Question

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Nguyễn Lê Phước Thịnh · Accepted Answer

Bài 1:

a: $\left\lbrack77-\left(-23\right)\right\rbrack\cdot54-\left\lbrack135+\left(-35\right)\right\rbrack\cdot\left(-6\right)$

$=\left(77+23\right)\cdot54+6\cdot100$

$=100\cdot\left(54+6\right)=60\cdot100=6000$

b: $99\left(123-56\right)+\left(-99\right)\left(-66+123\right)$

=99(123-56+66-123)

=99*10=990

c: $547-547\cdot\left(-103\right)+4\cdot\left(-547\right)$

$=547+547\cdot103-547\cdot4$

$=547\left(1+103-4\right)=547\cdot100=54700$

d: $\left(-76\right)\cdot2+76\cdot\left(-9\right)+76$

$=76\left(-2-9+1\right)$

$=76\cdot\left(-10\right)=-760$

Bài 4:

a: n-1∈Ư(n+4)

=>n+4⋮n-1

=>n-1+5⋮n-1

=>5⋮n-1

=>n-1∈{1;-1;5;-5}

=>n∈{2;0;6;-4}

b: 3n+7∈B(n+1)

=>3n+7⋮n+1

=>3n+3+4⋮n+1

=>4⋮n+1

=>n+1∈{1;-1;2;-2;4;-4}

=>n∈{0;-2;1;-3;3;-5}

c: 4n+3⋮n+2

=>4n+8-5⋮n+2

=>-5⋮n+2

=>n+2∈{1;-1;5;-5}

=>n∈{-1;-3;3;-7}

d: $n^2+3n-2$ ⋮n+2

=>$n^2+2n+n+2-4$ ⋮n+2

=>-4⋮n+2

=>n+2∈{1;-1;2;-2;4;-4}

=>n∈{-1;-3;0;-4;2;-6}

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