aa.1b=c00c

=>11.a.1b=91c.11

=>a.1b=91c

vì a.1b<19.10=190

=>91c<190

=>c<2

=>c=1=>91c=91=13.7

=>a=7;b=3

vậy a=7;b=3;c=1

Hey, bài này khó à nha. 

aaaaaaaaaaaaaaaaaaa

1;9;1

c=1

a=9

b=1

a] x=-6,-5,-4,-3,-2,

b] x=-2,-1,0,1,2

chúc học tốt

a) x ∈ {-6,-5,-4,-3,-2}

b) x ∈ {-2,-1,0,1,2}

b: =>2x-6=2

hay x=4

\(a,\left(x-1\right)^2=1\\ \Leftrightarrow\left[{}\begin{matrix}x-1=1\\x-1=-1\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=2\\x=0\end{matrix}\right.\\ b,7^2x-6=49\\ \Leftrightarrow49x=55\\ \Leftrightarrow x=\dfrac{55}{49}\)

Lời giải:
Cần bổ sung điều kiện $x$ là số nguyên.

a.

$2x+5\vdots x+1$

$\Rightarrow 2(x+1)+3\vdots x+1$

$\Rightarrow 3\vdots x+1$
$\Rightarrow x+1\in\left\{\pm 1; \pm 3\right\}$

$\Rightarrow x\in\left\{0; -2; 2; -4\right\}$

b.

$-x-5\vdots -x-1$

$\Rightarrow (-x-1)-4\vdots -x-1$

$\Rightarrow 4\vdots -x-1$

$\Rightarrow -x-1\in\left\{\pm 1; \pm 2; \pm 4\right\}$

$\Rightarrow x\in \left\{0; -2; 1; -3; 3; -5\right\}$

a: =>2x+2+3 chia hêt cho x+1

=>\(x+1\in\left\{1;-1;3;-3\right\}\)

=>\(x\in\left\{0;-2;2;-4\right\}\)

b: =>x+5 chia hết cho x+1

=>\(x+1\in\left\{1;-1;2;-2;4;-4\right\}\)

=>\(x\in\left\{0;-2;1;-3;3;-5\right\}\)

a) Có: -13 ⋮ x + 1

⇒ x + 1 ∈ Ư(-13)

⇒ x + 1 ∈ {-1; -13; 1; 13}

⇒ x ∈ {-2; -14; 0; 12}

b) Ta có: x ⋮ 5

⇒ x ∈ Ư(5)

⇒ x ∈ {1; 5; -1; -5}

Mà: -10 < x < 6

nên x ∈ {1; 5; -1; -5}