A=1+3+3^2+3^3+3^4+3^5+3^6+3^7 tinh 2A
Những câu hỏi liên quan
29 tháng 8 2023 lúc 19:22
b1 )
cho a 1+ 2^1 + 2^2 + 2^3^{ } +......+ 2^{2007}
a) tính 2a
b) chứng minh : a 2^{2006} - 1
b2 )
cho a 1+3+3^2 +3^3 +3^4 +3^5 + 3^6 + 3^7
a) tính 2a
b) chứng minh : a ( 3^8 - 1 ) : 2
Đọc tiếp
b1 )
cho a = 1+ 2\(^1\) + 2\(^2\) + 2\(^3\)\(^{ }\) +......+ 2\(^{2007}\)
a) tính 2a
b) chứng minh : a= 2\(^{2006}\) - 1
b2 )
cho a = 1+3+3\(^2\) +3\(^3\) +3\(^4\) +3\(^5\) + 3\(^6\) + 3\(^7\)
a) tính 2a
b) chứng minh : a= ( 3\(^8\) - 1 ) : 2
giúp mình với !!!!!!!!!!!!!!!!!!!!!!!!
Đúng 0
Bình luận (0)
Câu b, bài b1 chứng minh \(a=2^{2006}-1?\)
Đúng 1
Bình luận (0)
tinh bang cach thuan tien nhat a.3/5+4/7+2/5+1/7+2/7 b.1/3+1/6+4/3+2/6+2/3
tinh nhanh
a, 2/5 :3/7 * 3/7 :2/5 1999=
b, 1/2 * 2/3 :5/6 * 5/6 =
c, 2/3:4/5 : 5/6 : 8/7=
Cho a >b . Chứng minh : a)4a – 3 > 4b – 3; b) 1 – 2a < 1- 2b ; c) 5( a+ 3) - 4 > 5( b + 3) – 4; d)5 – 2a < 5 – 2b e) – 2 (1 – a) – 6 > -2 (1 – b ) – 6
a. Ta có: a > b
4a > 4b ( nhân cả 2 vế cho 4)
4a - 3 > 4b - 3 (cộng cả 2 vế cho -3)
b. Ta có: a > b
-2a < -2b ( nhân cả 2 vế cho -2)
1 - 2a < 1 - 2b (cộng cả 2 vế cho 1)
d. Ta có: a < b
-2a > -2b ( nhân cả 2 vế cho -2)
5 - 2a > 5 - 2b (cộng cả 2 vế cho 5)
Đúng 2
Bình luận (1)
BAI 1 : TINH NHANH BANG CACH THUAN TIEN NHAT :
A} 13/4 + 7/12 + 3/4 + 17/12
B} 1 VA 2/3 + 4 VA 4/7 + 5 VA 1/3 + 6 VA 3/7
C} 3/4 * 7/9 = 3/4 * 2/9
D} 3/4 * 4/5 * 5/6
BAI 3 : TINH
A} 3/4 CUA 16 KG .....
B} 7/12 CUA 840 M .....
C} 13/15 CUA 135 M3 .....
D} 6/7 CUA 280 L......
tinh (2/3-1/4+5/11)-(5-1/3-6/5)-(6-7/4+3/2)
\(\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right)-\left(5-\dfrac{1}{3}-\dfrac{6}{5}\right)-\left(6-\dfrac{7}{4}+\dfrac{3}{2}\right)\)
\(=\left(\dfrac{88-33+60}{132}\right)-\left(\dfrac{75-5-18}{15}\right)-\left(\dfrac{24-7+6}{4}\right)\)
\(=\dfrac{115}{132}-\dfrac{52}{15}-\dfrac{23}{4}\)
\(=-8\dfrac{19}{55}\)
Đúng 0
Bình luận (0)
Tinh nhanh : a)2 1/3 + 4 1/5 + 4 1/3
b)5 3/4 - 4 1/2 * 3 7/8
c)1 1/2 * 3 2/3 * 4 3/4
d)6 4/5 : 2 3/4 : 1 1/2
a, \(2\dfrac{1}{3}+4\dfrac{1}{5}+4\dfrac{1}{3}\)
\(=\dfrac{7}{3}+\dfrac{21}{5}+\dfrac{13}{3}\)
\(=\dfrac{1}{3}\left(7+13\right)+\dfrac{21}{5}\)
\(=\dfrac{20}{3}+\dfrac{21}{5}=\dfrac{100+63}{15}=\dfrac{163}{15}\)
b, \(5\dfrac{3}{4}-4\dfrac{1}{2}.3\dfrac{7}{8}\)
\(=\dfrac{23}{4}-\dfrac{9}{2}.\dfrac{31}{8}\)
\(=\dfrac{23}{4}-\dfrac{279}{16}=\dfrac{92-279}{16}=-\dfrac{187}{16}\)
c, \(1\dfrac{1}{2}.3\dfrac{2}{3}.4\dfrac{3}{4}\)
\(=\dfrac{3}{2}.\dfrac{11}{3}.\dfrac{19}{4}=\dfrac{209}{8}\)
d, \(6\dfrac{4}{5}:2\dfrac{3}{4}:1\dfrac{1}{2}\)
\(=\dfrac{34}{5}:\dfrac{11}{4}:\dfrac{3}{2}\)
\(=\left(\dfrac{34}{5}.\dfrac{4}{11}\right).\dfrac{2}{3}=\dfrac{136}{55}.\dfrac{2}{3}=\dfrac{272}{165}\)
Đúng 2
Bình luận (0)
Tinh Nhanh:
6 2/7 + 7 3/5 + 8 6/9 + 9 1/4 +2/5 + 5/7 + 1/3 + 3/4 + 1967
Tinh nhanh (3-1/4+2/3)-(5-1/3)-(6-7/4+3/2)