A) =(5+(-15))+(9+(-19))+(-11)+(13+17)+(21+(-23))

=(-10)+(-10)+(-11)+20+(-2)

=((-10)+(-10))+(-11)+(-2)+20

=(-20)+(-11)+20+(-2)

=((-20)+20)+((-11)+(-2))

=0+(-13)=-13

B) doi ti !!!!! Tich cho mik nha

Số số hạng của dãy là :

(29 - 11) : 2 + 1 = 10  số hạng

Tổng dãy trên là :

(29 + 11) x 10 : 2 = 200

Theo công thức lớp 6 nên ráng hiểu

C2 : Khoảng cách giữa mỗi số là 2

Số số hạng là :

( 29 - 11 ) : 2 + 1 = 10 ( số )

Tổng trên là :

( 29 + 11 ) x 10 : 2 = 200

                            Đáp số : 200

= (11+29) +(13+27) + (15+25) +(17+ 23 )+ (19+21)

=40 + 40 +40 +40 +40 

=5*40 = 200 

2+3-5-7+9+11-13-15+17+19-21-23+25=2

trả lời đầy đủ nhé

2+3-5-7+9+11-13-15+17+19-21-23+25=2

\(54:3^1+6.5^2\)
\(=54:3+6.25\)
\(=18+150\)
\(=168\)
\(---------\)
\(11-13+15-17+19-21+23-25\)
\(=\left(11-13\right)+\left(15-17\right)+\left(19-21\right)+\left(23-25\right)\)
\(=\left(-2\right)+\left(-2\right)+\left(-2\right)+\left(-2\right)\)
\(=\left(-2\right).4\)
\(=-8\)

mn giúp min bài này vs ạ

a)54 : 3³ + 6.5²

= 54 : 27 + 6.25

= 2 + 150

= 152

b) 45.26 + 45.74 - 1500

= 45.(26 + 74) - 1500

= 45.100 - 1500

= 4500 - 1500

= 3000

c) 125 + 132 + (-125) + (-21)

= [125 + (-125)] + [132 + (-21)]

= 0 + 111

= 111

d) 11 - 13 + 15 - 17 + 19 - 21 + 23 - 25

= -2 + (-2) + (-2) + (-2)

= (-4) + (-2) + (-2)

= (-8)

21 x 23 x 25 x 27 - 11 x 13 x 15 x 17

=(21-11)x(23-13)x(25-15)x(27-17)

=10x10x10x10

=10000

\(\text{21 x 23 x 25 x 27 - 11 x 13 x 15 x 17}\)

\(=\)\(483.675-143.\)\(255\)

\(=\)\(326025\)\(-\)\(36465\)

\(=\)\(289560\)

=21 x 23 x 25 x 27 - 11 x 13 x 15 x 17

=326025-36465

=289560

\(1+2+3+4+5+...+28+29=\left(1+29\right).29:2=435\)

(1+29)+(2+28)+(3+27)+(4+26)+(5+25)+(6+24)+(7+23)+(8+22)+(9+21)+(10+20)+(11+19)+(12+18)+(13+17)+(14+16)+15

=30+30+30+30+30+30+30+30+30+30+30+30+30+30+15

=30x14+15

=435

435

bạn lấy số đầu cộng số cuối được bao nhiêu cộng với 15

Bài 1:

a; \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{7}{21}\) + (- \(\dfrac{10}{36}\) + \(\dfrac{11}{19}\)  + \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)

=  \(\dfrac{5}{18}\) + \(\dfrac{8}{19}\) - \(\dfrac{1}{3}\) -\(\dfrac{10}{36}\) + \(\dfrac{11}{19}\) + \(\dfrac{1}{3}\) - \(\dfrac{5}{8}\)

= (\(\dfrac{5}{18}\) - \(\dfrac{10}{36}\)) + (\(\dfrac{8}{19}\) + \(\dfrac{11}{19}\)) - (\(\dfrac{1}{3}\) - \(\dfrac{1}{3}\)) - \(\dfrac{5}{8}\)

= (\(\dfrac{5}{18}\) - \(\dfrac{5}{18}\)) + \(\dfrac{19}{19}\) - 0 - \(\dfrac{5}{8}\)

= 0 + 1 - \(\dfrac{5}{8}\)

= \(\dfrac{3}{8}\)

b; \(\dfrac{1}{13}\) + (\(\dfrac{-5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\)) - (\(\dfrac{12}{17}\) - \(\dfrac{5}{18}\) + \(\dfrac{7}{5}\))

= \(\dfrac{1}{13}\) - \(\dfrac{5}{18}\) - \(\dfrac{1}{13}\) + \(\dfrac{12}{17}\) - \(\dfrac{12}{17}\) + \(\dfrac{5}{18}\) - \(\dfrac{7}{5}\)

= (\(\dfrac{1}{13}\) - \(\dfrac{1}{13}\)) + (\(\dfrac{12}{17}\) - \(\dfrac{12}{17}\)) + (-\(\dfrac{5}{18}\) + \(\dfrac{5}{18}\)) - \(\dfrac{7}{5}\)

= 0 + 0 + 0 - \(\dfrac{7}{5}\)

= - \(\dfrac{7}{5}\)

Bài 1 c;

   \(\dfrac{15}{14}\) - (\(\dfrac{17}{23}\) - \(\dfrac{80}{87}\) + \(\dfrac{5}{4}\)) + (\(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\))

=  \(\dfrac{15}{14}\) - \(\dfrac{17}{23}\) + \(\dfrac{80}{87}\) - \(\dfrac{5}{4}\) + \(\dfrac{17}{23}\) - \(\dfrac{15}{14}\) + \(\dfrac{1}{4}\)

= (\(\dfrac{15}{14}-\dfrac{15}{14}\)) + (\(-\dfrac{17}{23}+\dfrac{17}{23}\)) - (\(\dfrac{5}{4}\) - \(\dfrac{1}{4}\)) + \(\dfrac{80}{87}\)

= 0 + 0 - 1 + \(\dfrac{80}{87}\)

= - \(\dfrac{7}{87}\)

Bài 1 d; 

   \(\dfrac{1}{25}\) - \(\dfrac{4}{27}\) + (-\(\dfrac{23}{27}\) + \(\dfrac{-1}{25}\) - \(\dfrac{5}{43}\)) + \(\dfrac{5}{43}\) - \(\dfrac{4}{7}\)

= \(\dfrac{1}{25}\) - \(\dfrac{4}{27}\) - \(\dfrac{23}{27}\) - \(\dfrac{1}{25}\) - \(\dfrac{5}{43}\) + \(\dfrac{5}{43}\) - \(\dfrac{4}{7}\)

= (\(\dfrac{1}{25}\) - \(\dfrac{1}{25}\)) - (\(\dfrac{4}{27}\) + \(\dfrac{23}{27}\)) - (\(\dfrac{5}{43}\) - \(\dfrac{5}{43}\)) - \(\dfrac{4}{7}\)

= 0 - 1 - 0 - \(\dfrac{4}{7}\)

= \(\dfrac{-11}{7}\)