( 7/4+5/4) x 5/3= 12/4 x 5/3 = 3 x 5/3= 5

5

5

\(=\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=1+1=2\)

2

= 2

a, \(x\in\left\{-5;-4;-3;-2;-1;0;1;2;3;4;5\right\}\)

Tổng các x thoả mãn: (-5+5)+(-4+4)+(-3+3)+(-2+2)+(-1+1)+0=0+0+0+0+0+0=0

b, \(x\in\left\{-3;-2;-1;0;1;2\right\}\)

Tổng các x thoả mãn: (-2+2) + (-1+1) + 0 + (-3) = 0 + 0 + 0 + (-3) = -3

c, \(x\in\left\{-1;0;1;2;3;4\right\}\)

Tổng các x thoả mãn: (-1+1) + 0 + 2 + 3 + 4 = 9

Tương tự cháu làm các câu d,e,f rồi gửi lên lại thầy check cho hí

\(\text{a) -5 ≤ x < 6 }\)

\(x\in\left\{-5;-4;-3;-2;-1;0;1;2;3;4;5\right\}\)

\(\text{b) -4 < x < 3}\)

\(x\in\left\{-3;-2;-1;0;1;2\right\}\)
\(\text{c) -1 ≤ x ≤ 4}\)

\(x\in\left\{-1;0;1;2;3;4\right\}\)               

\(\text{d) -5 < x < 2}\)

\(x\in\left\{-4;-3;-2;-1;0;1\right\}\)
\(\text{e) -5 < x < 5 }\)

\(x\in\left\{-4;-3;-2;-1;0;1;2;3;4\right\}\)

\(\text{f) -6 < x ≤ 4}\)

\(x\in\left\{-5;-4;-3;-2;-1;0;1;2;3;4\right\}\)

=>x=406x12=4872

\(X:12=406\\ X=406\times12=4872\)

x=406.12

x=4872

=2/3+2/3=4/3

\(\dfrac{2}{3}+\dfrac{4}{5}\times\dfrac{5}{6}=\dfrac{2}{3}+\dfrac{2}{3}=\dfrac{4}{3}\)

`7/12 + 3/4 xx 2/9`

`= 7/12 + 6/36`

`= 7/12 + 1/6`

`= 7/12 + 2/12`

`= 9/12`

`= 3/4`

__

`8/9 - 4/15 : 2/5`

`= 8/9- 4/15 xx 5/2`

`= 8/9 - 20/30`

`= 8/9- 2/3`

`= 8/9- 6/9`

`= 2/9`

a)

`7/12+3/4xx2/9`

`=7/12+1/6`

`=7/12+2/12`

`=9/12`

`=3/4`

b)

`8/9-4/15:2/5`

`=8/9-4/15xx5/2`

`=8/9-2/3`

`=8/9-6/9`

`=2/9`

ai làm đúng e tích đúng cho

a: \(\Leftrightarrow\left(x-2010\right)\left(7x+1\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=2010\\x=-\dfrac{1}{7}\end{matrix}\right.\)

b: \(\Leftrightarrow\left(x-1\right)\left(x+1\right)=0\)

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

a)7x(x-2010)+(x-2010)=-

(x-2010)(7x+1)=0

x=2010 hoặc x=\(-\dfrac{1}{7}\)

Vậy \(x\in\left\{2010;-\dfrac{1}{7}\right\}\)

b)\(2x^2-2x=x^2-2x+1\)

\(2x^2-2x-x^2+2x-1=0\)

\(x^2-1=0\)

\(x^2=1\)

\(x=\pm1\)

Vậy \(x\in\left\{1;-1\right\}\)