Có phải đề số 1 là

(60-3).x-2.b.5.\(x^2\)=125

2.

35.20 + 35.80 + 15.80 + 15.20 = 35.(20 + 80) + 15.(80 + 20) = 35.100 + 15.100 = 3500 + 1500 = 50000

3.

S=(2+4+6+8+...+98+100) - (1+3+5+7+...+97+99)

S=\(\left\{\left[\left(100-2\right):2+1\right].\left(100+2\right):2\right\}\)\(-\left\{\left[\left(99-1\right):2+1\right].\left(99+1\right):2\right\}\)

S=2550-2500

S=50

\(\dfrac{\left[\left(\dfrac{3}{10}-\dfrac{4}{15}-\dfrac{7}{20}\right)\cdot\dfrac{5}{19}\right]}{\left[\dfrac{1}{14}+\dfrac{1}{7}-\dfrac{\left(-3\right)}{35}\right]\cdot\left(-\dfrac{4}{3}\right)}\)

\(=\dfrac{\left(\dfrac{18}{60}-\dfrac{16}{60}-\dfrac{21}{60}\right)\cdot\dfrac{5}{19}}{\left(\dfrac{5}{70}+\dfrac{10}{70}+\dfrac{6}{70}\right)\cdot\dfrac{-4}{3}}=\dfrac{\dfrac{-19}{60}\cdot\dfrac{5}{19}}{\dfrac{21}{70}\cdot\dfrac{-4}{3}}\)

\(=-\dfrac{1}{12}:\dfrac{-2}{5}=\dfrac{1}{12}\cdot\dfrac{5}{2}=\dfrac{5}{24}\)

=-35*(1+74+25)

=-35*100

=-3500

-35+35.(-74)-35.25

= -35.1+35.(-74)-35.25

= 35.( -1 )+35.(-74)-35.25

= 35 . [ ( -1 ) + ( -74 ) - 25 ]

= 35 . ( - 100 )

= -3500

-35 + 35 . ( -74 ) - 35 . 25

= -35 + 35 . [ ( -74 ) - 25 ]

= -35 + 35 . ( -99 )

= 35 . [ ( -99 ) - 1 ]

= 35 . ( -100 )

= -3500

  (-27).35-35.38+35.(-45)+35.10

=(-27).35+35.(-38)+35.(-45)+35.10

=35.[-27+(-38)+(-45)+10]

=35.(-100)

=-3500

( -27)  . 35 - 35 . 38 + 35. ( - 45 ) + 35 .10

= 35 . [ ( - 27 ) - 38 - 45 + 10 ]

= 35 . [ - 65 - 45 + 10 ]

= 35 . [ - 110 + 10 ]

= 35 . ( - 100)

= - 3500

@@ Học tốt

=35.(-27-38-45+10)

=35.(-100)

=-3500

25. ( − 5 ) .4. ( − 20 ) = 25.4. ( − 5 ) . ( − 20 ) = 100.100 = 10000

hình như bằng 0

hok tốt

85.[35-27]-35.[85-27]

=85.35-85.27-35.85+35.27

=85.27+35.27

=27(85+35)

=27.120

=3240

Bằng 0 thì mình ở nhà học cái gì nữa :] 

mà cảm ơn bạn wattif nhé

a) 5+96=101

3. 31-[26-(2017+35)]

=31-26-2017+35

=(31-26+35)-2017

=40-2017

=-1977

4. 54+(-37+10-54+67)

=54-37+10-54+67

=(54-54)-(37-67)+10

=0+30+10

=40