A,-3/-7+5/19+-4/7

=(-3/-7+-4/7)+5/19

=-1/7+5/19=16/133

B,-13/24+-5/24+7/21

=-3/4+7/21=-5/12

C,-5/13+(-8/13+1)

=(-5/13+-8/13)+1

=-1+1=0

D,2/3+(3/8+-2/3)

=(2/3+-2/3)+3/8

=0+3/8=3/8

E,(-3/4+5/8)+-1/8

=-1/8+1/8=0

456

nha ban

456 nha ban

giải rõ ra nha

nhóm các số có 2 chữ số với số đuôi tương tự.VD:(11-1)+(12-2)...

Chúc bạn làm đc

Bài làm:

1-2+3-4+5-6+7-8+9-10+11-12+13-14+15-16

= ( 1-2 ) + ( 3-4 ) + ( 5 -6 ) + ( 7- 8 ) + ( 9 - 10 ) + ( 11 - 12 ) + ( 13 -14 ) + ( 15-16 ) { có 8 nhóm } 

= ( -1 ) + ( -1 ) + ( -1 ) + ( -1 ) + ( -1 ) + ( -1 ) + ( -1 )+ ( -1 )

= ( -1 ) . 8

= 1 ( vì các số âm là số chẵn )

Đây là bài làm của mình, mình tính theo cách tính nhanh nha

KO HIỂU ?????

(-102)+[(-32).(-2)-(-8)]:13

=(-102)+[64-(-8)]:13

=(-102)+72:13

=(-102)+\(\frac{72}{13}\)

=-\(\frac{1254}{13}\)

(-102)+[64+8]:13

=(-102)+72:13

=(-102)+6

=-96

Tạm thời 72:13 bằng 6 nhé bạn vì 72 không chia hết cho 13

Đề yêu cầu gì vậy em?

đây là so sánh hay quy đồng v 

\(\dfrac{3}{5}v\text{à}\dfrac{7}{3}\\ MSC:15\\ \dfrac{3}{5}=\dfrac{3\times3}{5\times3}=\dfrac{9}{15};\dfrac{7}{3}=\dfrac{7\times5}{5\times3}=\dfrac{35}{15}\\ 9< 35\\ \Rightarrow\dfrac{3}{5}< \dfrac{7}{5}\\ \dfrac{9}{10}v\text{à}\dfrac{5}{4}\\MSC:20\\ \dfrac{9\times2}{10\times2}=\dfrac{18}{20};\dfrac{5}{4}=\dfrac{5\times5}{4\times5}=\dfrac{25}{20}\\ 18< 25\\ \Rightarrow\dfrac{9}{10}< \dfrac{5}{4}\\ \dfrac{2}{7}v\text{à}\dfrac{5}{4}\\ MSC:28\\ \dfrac{2}{7}=\dfrac{2\times4}{7\times4}=\dfrac{8}{28};\dfrac{5}{4}=\dfrac{5\times7}{4\times7}=\dfrac{35}{28}\\ 8< 35\\ \dfrac{2}{7}< \dfrac{5}{4}\\ \dfrac{8}{9}v\text{à}\dfrac{11}{6}\\ MSC:18\\ \dfrac{8\times2}{9\times2}=\dfrac{16}{18};\dfrac{11}{6}=\dfrac{11\times3}{6\times3}=\dfrac{33}{18}\\ 16< 33\\ \Rightarrow\dfrac{8}{9}< \dfrac{11}{6}\)

Quy đồng hả ?

\(\dfrac{3}{5}và\dfrac{7}{3}=\dfrac{3}{5}=\dfrac{3\times3}{5\times3}=\dfrac{9}{15};\dfrac{7}{3}=\dfrac{7\times5}{3\times5}=\dfrac{35}{15}\)

\(\dfrac{9}{10}và\dfrac{5}{4}=\dfrac{9}{10}=\dfrac{9\times2}{10\times2}=\dfrac{18}{20};\dfrac{5}{4}=\dfrac{5\times5}{4\times5}=\dfrac{25}{20}\)

\(\dfrac{2}{7}và\dfrac{5}{4}=\dfrac{2}{7}=\dfrac{2\times4}{7\times4}=\dfrac{8}{28};\dfrac{5}{4}=\dfrac{5\times7}{4\times7}=\dfrac{35}{28}\)

\(\dfrac{8}{9}và\dfrac{11}{6}=\dfrac{8}{9}=\dfrac{8\times2}{9\times2}=\dfrac{16}{18};\dfrac{11}{6}=\dfrac{11\times3}{6\times3}=\dfrac{33}{18}\)

\(\dfrac{6}{5}và\dfrac{13}{8}=\dfrac{6\times8}{5\times8}=\dfrac{48}{40};\dfrac{13}{8}=\dfrac{13\times5}{8\times5}=\dfrac{65}{40}\)

\(\dfrac{4}{5}và\dfrac{3}{2}=\dfrac{4}{5}=\dfrac{4\times2}{5\times2}=\dfrac{8}{10};\dfrac{3}{2}=\dfrac{3\times5}{2\times5}=\dfrac{15}{10}\)

\(\dfrac{5}{12}và\dfrac{7}{8}=\dfrac{5}{12}=\dfrac{5\times2}{12\times2}=\dfrac{10}{24};\dfrac{7}{8}=\dfrac{7\times3}{8\times3}=\dfrac{21}{24}\)

\(\dfrac{11}{4}và\dfrac{13}{6}=\dfrac{11}{4}=\dfrac{11\times3}{4\times3}=\dfrac{33}{12};\dfrac{13}{6}=\dfrac{13\times2}{6\times2}=\dfrac{26}{12}\)

a: =(8/27+19/27)+(4/15+11/15)=1+1=2

b: =(12/13+8/13+6/13)+(2/7+5/7)=2+1=3

\(P=sin^2x+3cos^2x=1-cos^2x+3cos^2x=1+2cos^2x=1+2.\left(\dfrac{1}{4}\right)^2=\dfrac{9}{8}\)

3: \(=\dfrac{13}{5}\left(-\dfrac{3}{14}+\dfrac{2}{5}+\dfrac{-11}{14}+\dfrac{3}{5}\right)\)

=0