1223-1223=0

Tk mk nha

1223 - 1223 = 0 .

Chúc bạn học tốt !

1223 -1223=0

\(\Leftrightarrow x+30=0\)

hay x=-30

\(x-\left(-19\right)-\left(-11\right)=0\)

⇔\(x+19+11=0\)

⇔\(x+30=0\)

⇔\(x=-30\)

x+19+11=0

x+19=-11

x=-30

   

124691

Lên lớp mách cô dám hỏi bái

a) \(\dfrac{2}{5}\cdot\dfrac{1}{7}+\dfrac{2}{5}\cdot\dfrac{5}{7}+\dfrac{2}{5}\)

\(=\dfrac{2}{5}\left(\dfrac{1}{7}+\dfrac{5}{7}+1\right)\)

\(=\dfrac{2}{5}\cdot\dfrac{13}{7}=\dfrac{26}{35}\)

b) \(\dfrac{1}{5}+\dfrac{2}{8}+\dfrac{4}{5}+\dfrac{7}{8}-\dfrac{1}{8}\)

\(=\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\left(\dfrac{2}{8}+\dfrac{7}{8}-\dfrac{1}{8}\right)\)

\(=1+1=2\)

c)\(\dfrac{24}{36}\cdot\dfrac{10}{12}\cdot36\)

\(=\dfrac{24\cdot10\cdot36}{36\cdot12}=\dfrac{12\cdot2\cdot10\cdot36}{12\cdot36}\)

\(=2\cdot10=20\)

* x+23=56

     x   =56-23

     x   =33

* x+1223=45

x           =45-1223

x           =-1178

x + 23 = 56

\(\Leftrightarrow\)x = 56 - 23 = 33

x + 1223 = 45

\(\Leftrightarrow\)x = 45 - 1223 = -1178

x1=33

x2=-1178

2457 nha

1223+1234= 2457

1223+1234=2457

Đáp án cần chọn là: B

Vì −12 < −8 nên  − 12 23 < − 8 23