a) 237 . ( -26 ) + 26 . 137

=  ( - 237 ) . 26 + 26 . 137

= 26 . [ ( -237 ) + 137 ]

= 26 . ( -100 )

= -2600

b) 63 . ( -25 ) + 25 . ( -23 )

= ( -63 ) . 25 + 25 . ( -23 )

= 25 . [ ( -63 ) + ( -23 ) ]

= 25 . ( -86 )

= -2150

= -237. 26 + 26. 137

26.( - 237 + 137 )

=26.  (-100)

= -2600

a) 237.(-26) + 26.137

= -237.26 + 26.137

= 26.(-237 + 137)

= 26.(-100)

= -2600

b) 63.(-25) + 25.(-23)

= -63.25 + 25.(-23)

= 25.(-63 - 23)

= 25.(-86)

= -2150

=63 . (-25 ) + (-25).23

-25 .(63+ 23)

-25 . 86

= -2150

Trả lời :

Sử dụng tổng xích ma nha ( k biết bấm thì bảo tui )

B = -10

Study well 

\(=\left(28^2-27^2\right)+\left(26^2-25^2\right)+....+\left(2^2-1^2\right)\)

\(=\left(28-27\right)\left(28+21\right)+\left(26-25\right)\left(26+25\right)+...+\left(2-1\right)\left(2+1\right)\)

\(=55+51+...+3\)

\(=\frac{\left[\left(55-3\right):4+1\right]\left(55+3\right)}{2}\)

\(=406\)

Lê Tài Bảo Châu làm đúng rồi nha em !!!

237 . ( -26 ) + 26 . 137

= ( -237 ) . 26 + 26 . 137

= 26 . [ ( -237 ) + 137 ]

= 26 . ( -100 )

= -2600

63 . ( -25 ) + 25 . ( -23 )

= ( -63 ) . 25 + 25 . ( -23 )

= 25 . [ ( -63 ) + ( -23 ) ]

= 25 . ( -86 )

= -2150

237.(-26)+26.137 

= -237.26+26.137

= 26.(-237+137)

= 26.-100

= -2600

63.(-25)+25.(-23)

= -63.25+25.(-23)

= 25.[-63+(-23)]

= 25.(-86)

= -2150

237 . (-26)+26.137 

=-6162 + 3562

=-2600

*63 .(-25)+25.(-23)

=-1575 + -575

=-2150

a) (-24) + 6 + 10 + 24

= [(-24) + 24] + 6 + 10

= 0 + 6 + 10

= 16

b) 15 + 23 + (-25) + (-23)

= [15+ (-25)] + [23 +(-23)]

= -10 + 0

= -10

c) (-3) + (-350) + (-7) + 350

=[-350 + 350] + [-3+(-7)]

= 0 + (-10)

= -10

d) (-9) + (-11) +21 + (-1)

= [ (-9) + (-11) ] + [ 21 + (-1)]

= -20 + 20

= 0

a) \(\left(-24\right)+6+10+24\)

\(=16\)

b) \(15+23+\left(-25\right)+\left(-23\right)\)

\(=-10\)

c) \(\left(-3\right)+\left(-350\right)+\left(-7\right)+350\)

\(=-10\)

d) \(\left(-9\right)+\left(-11\right)+21+\left(-1\right)\)

\(=0\)

\(a,\left(-24\right)+6+10+24\)

=\(\left[\left(-24\right)+24\right]+6+10\)

\(=0+16=16\)

b, \(15+23+\left(-25\right)+23\)

\(=\left[15+\left(-25\right)\right]+\left[\left(-23\right)+23\right]\)

\(=-10+0=-10\)

c, \(\left(-3\right)+\left(-350\right)+\left(-7\right)+350\)

\(=\left[\left(-3\right)+\left(-7\right)\right]+\left\{\left(-350\right)+350\right\}\)

\(=-10+0=-10\)

d, \(\left(-9\right)+\left(-11\right)+21+\left(-1\right)\)

\(=\left\{\left(-9\right)+\left(-11\right)\right\}+\left[21+\left(-1\right)\right]\)

\(=-20+20=0\)

a)

\(\begin{array}{l}A = \frac{5}{{11}}.\left( {\frac{{ - 3}}{{23}}} \right).\frac{{11}}{5}.\left( { - 4,6} \right)\\A = \frac{5}{{11}}.\left( {\frac{{ - 3}}{{23}}} \right).\frac{{11}}{5}.\frac{{ - 23}}{5}\\A = \frac{{5.\left( { - 3} \right).11.\left( { - 23} \right)}}{{11.23.5.5}}\\A = \frac{3}{5}\end{array}\)  

b)

\(\begin{array}{l}B = \left( {\frac{{ - 7}}{9}} \right).\frac{{13}}{{25}} - \frac{{13}}{{25}}.\frac{2}{9}\\B = \frac{{13}}{{25}}.\left( {\frac{{ - 7}}{9} - \frac{2}{9}} \right)\\B = \frac{{13}}{{25}}.(-1)\\B = \frac{{-13}}{{25}}.\end{array}\)

1. = 13

2. = 346

3.= -69

4. = -2600

5. -2150

a. \(\frac{x-23}{24}+\frac{x-23}{25}=\frac{x-23}{26}+\frac{x-23}{27}\)

\(\Leftrightarrow\left(x-23\right)\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)=0\)

\(\Leftrightarrow x=23\) (Vì \(\left(\frac{1}{24}+\frac{1}{25}-\frac{1}{26}-\frac{1}{27}\right)\ne0\) )

b. \(\left(\frac{x+2}{98}+1\right)+\left(\frac{x+3}{97}+1\right)=\left(\frac{x+4}{96}+1\right)+\left(\frac{x+5}{95}+1\right)\)

\(\Leftrightarrow\frac{x+100}{98}+\frac{x+100}{97}-\frac{x+100}{96}-\frac{x+100}{95}=0\)

\(\Leftrightarrow\left(x+100\right)\left(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\right)=0\)

\(\Leftrightarrow x=-100\) (Vì \(\left(\frac{1}{98}+\frac{1}{97}-\frac{1}{96}-\frac{1}{95}\right)\ne0\) )