Question

a, 5 . (x-1)²  = 45             

    b, x + 4 ⁝ x – 1          

       c) (x + 1). (2 – y) = - 5

Answer 1

a) \(5\cdot\left(x-1\right)^2=45\)

\(\Rightarrow\left(x-1\right)^2=45:5\)

\(\Rightarrow\left(x-1\right)^2=9\)

\(\Rightarrow\left(x-1\right)^2=3^2\)

\(\Rightarrow\left[{}\begin{matrix}x-1=3\\x-1=-3\end{matrix}\right.\)

\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-2\end{matrix}\right.\)

b) x + 4 ⋮ x - 1 

⇒ x - 1 + 5 ⋮ x - 1 

⇒ 5 ⋮ x - 1

Vậy: \(x-1\in\text{Ư}\left(5\right)\)

Mà: \(\text{Ư}\left(5\right)=\left\{1;-1;-5;5\right\}\)

\(\Rightarrow x\in\left\{2;0;-4;6\right\}\)

c) \(\left(x+1\right)\left(2-y\right)=-5\)

Ta có bảng sau:

\(x+1\)	1	-1	-5	5
\(2-y\)	-5	5	1	-1
\(x\)	0	-2	-6	4
\(y\)	7	-3	1	3

Vậy các cặp (x;y) thỏa mãn là: (0;7) ; (-2;-3) ; (-6;1) ; (4;3)

Answer 2

0,7

-2,-3

-6,1

4,3