giải mik câu này nữa , ai nhanh mik tik :
tinh nhanh :
C = ( \(\frac{21}{31}\)+\(\frac{-6}{17}\)) + (\(\frac{-44}{33}\)+ \(\frac{10}{31}\)) +\(\frac{9}{53}\)
giải cho mình 2 bài toán này nha , ai nhanh mình tik cho !
tính nhanh : nhưng ra từng bước nha , ai nhanh mink tik
1) C = (\(\frac{21}{31}\)+\(\frac{-16}{7}\)) +(\(\frac{-44}{33}\)+\(\frac{10}{31}\)) +\(\frac{9}{53}\)
Tính hợp lí:
a, \(\frac{-3}{4}+\frac{3}{7}+\frac{-1}{4}+\frac{4}{9}+\frac{4}{7}\)
b, \(\frac{-7}{9}.\frac{4}{11}+\frac{-7}{9}.\frac{7}{11}+5\frac{7}{9}\)
c,\(\left(\frac{21}{31}+\frac{2013}{6039}\right)-\left(\frac{44}{53}-\frac{10}{31}\right)-\frac{9}{53}\)
giúp mik vs mik cần gấp lắm
\(a)\frac{-3}{4}+\frac{3}{7}+-\frac{1}{4}+\frac{4}{9}+\frac{4}{7}\)
\(=\left(\frac{-3}{4}+-\frac{1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)
\(=-1+1+\frac{4}{9}\)
\(=\frac{4}{9}\)
\(\frac{-3}{4}+\frac{3}{7}+\frac{-1}{4}+\frac{4}{9}+\frac{4}{7}\)
\(=\left(\frac{-3}{4}+\frac{-1}{4}\right)+\left(\frac{3}{7}+\frac{4}{7}\right)+\frac{4}{9}\)
\(=\left(-1\right)+1+\frac{4}{9}\)
\(=0+\frac{4}{9}\)
\(=\frac{4}{9}\)
Tính hợp lí
\(A=\left(\frac{21}{31}+\frac{-16}{7}\right)+\left(\frac{44}{53}+\frac{10}{21}\right)+\frac{9}{53}\)
\(B=\frac{6}{15.18}+\frac{6}{18.21}+...+\frac{6}{87.90}\)
\(A=\frac{21}{31}+\frac{-16}{7}+\frac{44}{53}+\frac{10}{21}+\frac{9}{53} \)
\(A=\left(\frac{16}{7}+\frac{10}{21}\right)+\left(\frac{44}{53}+\frac{9}{53}\right)+\frac{21}{31}\)
\(A=\frac{58}{21}+1+\frac{21}{31}\)
\(A=\frac{100}{21}\)
\(B=6\left(\frac{1}{15.18}+\frac{1}{18.21}+...+\frac{1}{87.90}\right)\)
\(B=6\left(\frac{1}{15}-\frac{1}{18}+\frac{1}{18}-\frac{1}{21}+...+\frac{1}{87}-\frac{1}{90}\right)\)
\(B=6\left(\frac{1}{15}-\frac{1}{90}\right)\)
\(B=6.\frac{1}{18}\)
\(B=\frac{1}{3}\)
\(\frac{21}{31}+\frac{2013}{6039}-\frac{44}{53}-\frac{10}{31}-\frac{9}{53}\)
\(\left(\frac{21}{31}-\frac{10}{31}\right)-\left(\frac{44}{53}+\frac{9}{53}\right)+\frac{1}{3}\)
\(\frac{11}{31}-1+\frac{1}{3}\)
\(\frac{-29}{93}\)
\(\left(\frac{21}{31}+\frac{2013}{6039}\right)-\left(\frac{44}{53}-\frac{10}{31}\right)-\frac{9}{53}\)
Thực hiện phép tính
= 21/31 + 1/3 - 44/53 + 10/31 -9/53
= [21/31+10/31] - [44/53 + 9/53] +1/3
= 1-1+1/3 = 1/3
Tinh bang cach hop li
a) \(\left(\frac{1}{4}+\frac{-5}{13}\right)\)+ \(\left(\frac{2}{11}+\frac{-8}{13}+\frac{3}{4}\right)\)
b)\(\left(\frac{21}{31}+\frac{-16}{7}\right)\)+\(\left(\frac{44}{53}+\frac{10}{31}\right)+\frac{9}{53}\)
a)(1/4+3/4)-(5/13+8/13)+2/11=1-1+2/11=2/11
b)(21/31+10/31)-16/7+(44/53+9/53)=1+1-16/7=14/7-16/7=-2/7
bằng2/11
-16/7
a, \(\left(\frac{1}{4}+\frac{-5}{13}\right)+\left(\frac{2}{11}+\frac{-8}{13}+\frac{3}{4}\right)\)
\(=\left(\frac{1}{4}-\frac{5}{13}\right)+\left(\frac{2}{11}-\frac{8}{13}+\frac{3}{4}\right)\)
\(=\frac{1}{4}-\frac{5}{13}+\frac{2}{11}-\frac{8}{13}+\frac{3}{4}=1-1+\frac{2}{11}=\frac{2}{11}\)( vì \(\left(\frac{1}{4}+\frac{3}{4}\right)+\left(-\frac{5}{13}-\frac{8}{13}+\frac{2}{11}\right)\))
b, \(\left(\frac{21}{31}+\frac{-16}{7}\right)+\left(\frac{44}{53}+\frac{10}{31}\right)+\frac{9}{53}\)
\(=\frac{21}{31}-\frac{16}{7}+\frac{44}{53}+\frac{10}{31}+\frac{9}{53}\)
\(=1-\frac{16}{7}+1=\frac{7}{7}-\frac{16}{7}+\frac{7}{7}=-\frac{2}{7}\)
16 tính bằng cách hợp lí
a) ( \(\frac{1}{4}\)+ \(\frac{-5}{13}\)) + ( \(\frac{2}{11}+\frac{-8}{13}+\frac{3}{4}\))
b) ( \(\frac{21}{31}+\frac{-16}{7}\)) +( \(\frac{44}{53}\)+ \(\frac{10}{31}\)) +\(\frac{9}{53}\)
c) \(\frac{-5}{7}+\frac{3}{4}+\frac{-1}{5}+\frac{-2}{7}+\frac{1}{4}\)
d) \(\frac{-3}{31}+\frac{-6}{17}+\frac{1}{25}+\frac{-28}{31}+\frac{-11}{17}+\frac{-1}{5}\)
tính nhanh
\(\frac{1}{2}+\frac{2}{3}+\frac{3}{4}+\frac{4}{5}+\frac{5}{6}+\frac{6}{7}+\frac{7}{8}+\frac{8}{9}+\frac{9}{10}\)\(\frac{9}{10}\)
ai nhanh mik tik nha
1/2+2/3+3/4+4/5+5/6+6/7+7/8+8/9+9/10x9/10
=9/10x(1/2+2/3)+(3/4+4/5)+(5/6+6/7)+(7/8+8/9)
=9/10x(1/3+3/5+5/7+7/9)
9/10x(1/3+3/5)+(5/7+7/9)
=9/10x1/5+5/9
9/50+5/9
=10
Bn Long làm đúng rồi bn nguyễn kim arica cứ làm theo cách đó là được .
Bn nào thấy đúng thì ủng hộ nha .
hình như đề bạn sai thì phải đúng ko biết ngỏ bạn làm
cái chỗ có 2 phân số 9/10 đấy
Tính hợp lí ( nếu có thể )
a) \(\left(\frac{-3}{42}+\frac{10}{-21}-\frac{-9}{14}\right).\left(\frac{-7}{5}\right)\)
Các bn giúp mik với
Ai nhanh mik cho 3 tik
\(\left(\frac{-3}{42}+\frac{10}{-21}-\frac{-9}{14}\right).\left(\frac{-7}{5}\right).\)
\(=\left(\frac{-1}{14}-\frac{10}{21}+\frac{9}{14}\right).\left(\frac{-7}{5}\right)\)
\(\left(\frac{12}{21}-\frac{10}{21}\right).\left(\frac{-7}{5}\right)=\frac{2.\left(-7\right)}{21.5}=\frac{-2}{15}\)