\(A=\frac{58}{89}\times\frac{51}{76}-\frac{28}{89}\times\frac{51}{79}+\frac{51}{89}\times\frac{23}{38}\)
Tính nhnh giá trị biểu thức sau: S = \(\frac{58}{89}\).\(\frac{51}{76}\)-\(\frac{28}{98}\).\(\frac{51}{76}\)+\(\frac{51}{89}\).\(\frac{23}{38}\)
Giúp mình với ạ :D
Tính nhanh biếu thức sau: S = \(\frac{58}{89}\).\(\frac{51}{76}\)-\(\frac{28}{98}\).\(\frac{51}{76}\)+\(\frac{51}{89}\).\(\frac{23}{38}\)
Giúp mình với ạ :D
Chứng tỏ rằng: \(\frac{1}{1}\times\frac{1}{3}\times\frac{1}{5}\times.....\times\frac{1}{99}=\frac{2}{51}\times\frac{2}{52}\times\frac{2}{53}\times.....\times\frac{2}{100}\)
VÌ 1/1.1/3.......1/99=2/51.2/52.........2/100
VÀ 2/51.2/52.....2/100=1/1.1/3.......1/99
SUY RA BẰNG NHAU
tính bằng cách thuận tiện
a. \(\frac{1}{2}\times\frac{2}{3}\div\frac{4}{3}\times\frac{4}{5}\div\frac{6}{5}\times\frac{6}{7}\div\frac{7}{8}\times\frac{8}{9}\div\frac{10}{9}\)
b.\(\frac{27}{49}\times\frac{49}{50}\times\frac{15}{51}\times(\frac{5}{10}-\frac{1}{2})\)
(7x6=5+2+6x7) =
SO SÁNH
C= \(1\times3\times5\times7\times...\times99\) VOI D=\(\frac{51}{2}\times\frac{52}{2}\times\frac{53}{2}\times...\times\frac{100}{2}\)
tính \(\frac{1}{5}\left(\frac{1}{4}-\frac{1}{49}\right)\times\frac{1-\left(3+5+7+...+49\right)}{89}\)
bài 20 tính bằng phương pháp hợp lí nhất
a \(\frac{31}{23}-\left(\frac{7}{32}+\frac{8}{23}\right)\)
b \(\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
c\(\frac{38}{45}-\left(\frac{8}{45}-\frac{17}{51}-\frac{3}{11}\right)\)
Tính bằng cách hợp lý nhất:
a, \(\frac{31}{23}-\left(\frac{7}{32}+\frac{8}{23}\right)\)
b, \(\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
c, \(\frac{38}{45}-\left(\frac{8}{45}-\frac{17}{51}-\frac{3}{11}\right)\)
Các bạn ơi giúp mk với!*****
a) 31/23 - ( 7/32 + 8/22)
= 31/23 - 7/32 + 8/23
= ( 31/23 + 8/23 ) - 7/32
= 32/22 - 7/32
= 39/32
Ccá ý khác làm tương tự
=(31\23-8\23)+7\32
=23\23+7\32
=1+7\32
=39\32
1) Tính hợp lý
a)\(\frac{31}{23}-\left(\frac{7}{32}+\frac{8}{32}\right)\)
b)\(\left(\frac{1}{3}+\frac{12}{67}+\frac{13}{41}\right)-\left(\frac{79}{67}-\frac{28}{41}\right)\)
c)\(\frac{38}{45}-\left(\frac{8}{45}-\frac{17}{51}-\frac{3}{11}\right)\)
d)\(\left(\frac{17}{28}+\frac{18}{29}-\frac{19}{30}-\frac{30}{31}\right).\left(-\frac{5}{12}+\frac{1}{4}+\frac{1}{6}\right)\)
Trả lời
b)(1/3+12/67+13/41)-(79/67-28/41)
=1/3+12/67+13/41-79/67+28/41
=1/3+(12/67-79/67)+(13/41+28/41)
=1/3+(-67/67)+41/41
=1/3+(-1)+1
=1/3+0
=1/3.
c)38/45-(8/45-17/51-3/11)
=38/45-8/45+17/51+3/11
=30/45+1/3+3/11
=2/3+1/3+3/11
=3/3+3/11
=1+3/11
=1 3/11.
d)(17/28+18/29-19/30-30/31).(-5/12+1/4+1/6)
=(17/28+18/29+19/30+30/31).(-5+3+2/12)
=(17/28+18/29+19/30+30/31).0
=0.