(26 – 6).(-4) + 31.(-7 -13) = 20.(-4) + 31.(-20) = -80 + (-620) = -700

(26 - 6) . (-4) +31 . (-7-13) = 20 . (-4) + 31 . (-20)

                                     = 20 . (-4) + (-31) . 20

                                     = 20 . [-4 + (-31)]

                                     = 20. (-35)

                                     = -700

(26-6).(-4)+31.(-7-13)

=20.(-4)+31.(-20)

=(-80)+(-620)

=-700

Hợp lí rồi đó.Tk nh.Chúc bạn học giỏi

(26-6).(-4)+31.(-7-13)

=20.(-4)+31.(-20)

=20.(-4)+(-31).20

=20.[(-4)+(-31)]

=20.(-34)

=-680

(26-6).(-4)+31.(-7-13)

=20.27.(-20)

=540.(-20)

=-10800

lớp 1 mà cậu

4.24.5²-(3³.18+3³.12)

=4.24.25-[27.(18+12)]

=(4.25).24-[27.30]

=100.24-810

=2400-810

=1590

4.24.5^2-(3^3.18+3^3.12)

31.15.7^2.4-31.49.40

1+2+3+4+5+6+7+8+9+10

1+3+5+7+9+11+13+15+19

2+6+10+14+22+23+26+34

5+8+11+14+17+20+23+26+29

1+6+11+16+21+26+31+36+41+47+51

10+13+16+19+22+25+28+31+34+37+40

5+7+9+11+13+15+17+3+8+13+18+23+28

4+7+10+13+16+19+5+9+13+17+21+25 = 1590

#HT#

(-1)+-39/13

-700

-3400

-12700

-820 

Tích cho mk nha

Giải chi tiết cho mình nha

\(\dfrac{2}{5}+\dfrac{11}{15}=\dfrac{6}{15}+\dfrac{11}{15}=\dfrac{17}{15}\)

\(\dfrac{7}{8}-\dfrac{7}{9}=\dfrac{63}{72}-\dfrac{56}{72}=\dfrac{7}{72}\)

\(\dfrac{11}{13}\times\dfrac{26}{31}=\dfrac{22}{31}\)

\(\dfrac{16}{24}:4=\dfrac{16}{24}\times\dfrac{1}{4}=\dfrac{4}{24}=\dfrac{1}{6}\)

\(30:\dfrac{6}{5}=30\times\dfrac{5}{6}=25\)

\(\dfrac{9}{16}:4=\dfrac{9}{16}\times\dfrac{1}{4}=\dfrac{9}{64}\)

\(\dfrac{1}{2}:\dfrac{1}{3}\times\dfrac{8}{15}=\dfrac{1}{2}\times3\times\dfrac{8}{15}=\dfrac{4}{5}\)

2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5

b) 52

a, ( 26 - 6) . (-4) + 31. (-7-13)

=20 . ( -4) + 31.(-20)

=(-80) + (-620)

= (-700)

b,4.(-5)^2 - 6.(26-21)

=4.25 - 6.5

= 100- 30

=70

c,56.(-24) + 24.(-44)

=(-1334)+(-1056)

= -2390