Kết quả cuối cùng của mình \(=34\) 

Chúc bạn học giỏi

30+12+(-20)-(-12)

=12+(-12)+30-(-2

=0+10=10

30 + 12 + ( - 20 ) - ( - 12 )

= 30 + 12 - 20 + 12

= 30 - 20 + ( 12 - 12 )

= 10 + 0

= 10

\(1)\frac{11}{12}-\frac{5}{12}\left(0,8-\frac{1}{10}\right):\left(-\frac{7}{12}\right)\)

\(=\frac{11}{12}-\frac{5}{12}\times\frac{7}{10}:\left(-\frac{7}{12}\right)\)

\(=\frac{11}{12}-\frac{7}{24}:\left(-\frac{7}{12}\right)\)

\(=\frac{11}{12}-\left(-\frac{1}{2}\right)\)

\(=\frac{17}{12}\)

\(d,-\dfrac{5}{12}+\dfrac{3}{4}=-\dfrac{5}{12}+\dfrac{9}{12}=\dfrac{4}{12}=\dfrac{1}{3}\)

\(e,\dfrac{5}{7}.\dfrac{25}{2}-\dfrac{5}{7}.\dfrac{11}{2}=\dfrac{5}{7}.\left(\dfrac{25}{2}-\dfrac{11}{2}\right)=\dfrac{5}{7}.7=5\)

1) 5 + (-4) = 1

2) (-8) + 2 = -6

3) 8 + (-2) = 6

4) 11 + (-3) = 8

5) (-11) + 2 = -9

6) (-7) + 3 = -4

7) (-5) + 5 = 0

8) 11 + (-12) = -1

9) (-18) + 20 = 2

10) (15) + (-12) = 3

11) (-17) + 17 = 0

12) 16 + (-2) = 14

13) (30) + (-14) = 16

14) (-19) + 20 = 1

15) (-18) + 15 = -3

16) (10) + (-6) = 4

17) (-28) + 14 = -14

18) 15 + (-30) = -15

19) (15) + (-4) = 11

20) (-21) + 11 = -10

21) 8 + (-22) = -14

22) (-15) + 4 = -11

23) (-3) + 2 = -1

24) 17 + (-14) = 3

25) 17 + (-14) = 3

thế này đọc đc mới đỉnh

a) \(x+5=2015-\left(12-7\right)\)

\(\Leftrightarrow x+5=2015-5\)\(\Leftrightarrow x+5=2010\)

\(\Leftrightarrow x=2005\)

Vậy \(x=2005\)

b) \(-7\left|x+3\right|=-49\)\(\Leftrightarrow\left|x+3\right|=7\)

\(\Leftrightarrow\orbr{\begin{cases}x+3=-7\\x+3=7\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-10\\x=4\end{cases}}\)

Vậy \(x=-10\)hoặc \(x=4\)

c) \(\left(105-x\right):2^5=2015^0+1\)

\(\Leftrightarrow\left(105-x\right):32=1+1\)\(\Leftrightarrow\left(105-x\right):32=2\)

\(\Leftrightarrow105-x=64\)\(\Leftrightarrow x=41\)

Vậy \(x=41\)

a. x+5 = 2015-(12-7)

x+5= 2015-5

x+5 = 2010

x=2005

b, -7/ x+3/ =-49

/x+3/ = 7

x+3 = 7 suy ra x=4

hoặc x+3= -7 suy ra x=-10

c. (105-x) : 2^5= 2015^0 + 1

(105-x) : 32= 1+1

(105-x) : 32= 2

105-x= 64

x= 41

Cái này kiến thức cơ bản thôi ạ

\(a,=\dfrac{21}{48}+\dfrac{10}{48}=\dfrac{31}{48}\\ b,=\dfrac{44}{60}-\dfrac{25}{60}=\dfrac{19}{60}\)

Ta có:

\(12:\left\{390:\left[500-\left(5^3+7^2.5\right)\right]\right\}\)

\(=12:\left\{390:\left[500-125-245\right]\right\}\)

\(=12:\left(390:130\right)\)

\(=12:3=4\)

=4                         

         \(\frac{\frac{2}{3}-\frac{1}{4}+\frac{5}{11}}{\frac{5}{12}-1-\frac{7}{11}}\)

\(=\frac{\frac{88}{132}-\frac{33}{132}+\frac{60}{132}}{\frac{55}{132}-\frac{132}{132}+\frac{84}{132}}\)

\(=\frac{\frac{115}{132}}{\frac{7}{132}}\)

\(=\frac{115}{132}\div\frac{7}{132}\)

\(=\frac{115}{7}\)