T= \(\dfrac{2}{3}.\dfrac{4}{5}.\dfrac{6}{7}.\dfrac{8}{9}.\dfrac{10}{11}.\dfrac{1}{2}.\dfrac{3}{4}.\dfrac{5}{6}.\dfrac{7}{8}.\dfrac{9}{10}\)
T=\(\dfrac{2.4.6.8.10.1.3.5.7.9}{3.5.7.9.11.2.4.6.8.10}\)
T=\(\dfrac{1.1.1.1.1.1.1.1.1.1}{1.1.1.1.11.1.1.1.1.1}\)
T=\(\dfrac{1}{11}\)
2/5-2/9+2/11/7/5-7/9+7/11:1/3-1/4+1/5/7/6-7/8+7/10:tính nhanh
Hãy điền các dấu +,-,x,:,( ), ngoặc vuông, ngoặc nhọn,... để kết quả là -1
1...2...3...4=-1
1...2...3...4...5=-1
1...2...3...4...5...6=-1
1...2...3...4...5...6...7=-1
1...2...3...4...5...6...7...8=-1
1...2...3...4...5...6...7...8...9=-1
1...2...3...4...5...6...7...8...9...10=-1
tính giá trị biểu thức sau
A= -1 -2 +3 +4 -5 -6 +7 +8-9-10+11+12 -...........-2013-2014+2015+2016
B= [\(\dfrac{1}{2}\) -1 ] : [\(\dfrac{1}{3}\) -1] : ...................: [\(\dfrac{1}{99}\) -1} : [\(\dfrac{1}{100}\) -1]
1. Tính giá trị biểu thức:
M=\(1+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{100}}\)
2.Chứng tỏ rằng :
\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{100^2}< 1\)
3.So sánh
a, A=\(\dfrac{11^5+1}{11^6+1}\) ; B=\(\dfrac{11^6+1}{11^7+1}\)
b, M=\(\dfrac{15^{10}-1}{15^9+1}\) ; N=\(\dfrac{15^9-1}{15^{10}+1}\)
Tính nhanh giá trị biểu thức sau:
a) \(-\frac{9}{10}\cdot\frac{5}{14}+\frac{1}{10}\cdot\left(-\frac{9}{2}\right)+\frac{1}{7}\cdot\left(-\frac{9}{10}\right)\)
b)\(\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{6}+\frac{1}{11}\right)\cdot132\)
c)\(-\frac{2}{3}\cdot\left(\frac{8}{9}\cdot\frac{8}{13}-\frac{8}{27}\cdot\frac{3}{13}+\frac{4}{3}\cdot\frac{22}{39}\right)\)
1. | 4-2x | . 1/3 = 1/3
2. (-3)² : | x+(-1) | = (-3)
3. | 3/2 -x | + (-4/5) = -14/5
4. (-4/3) - | 2x + (-1) | = -7/3
5. -9 . | 36 - x/2 | = (-54)
6. 0,75 - | (-x) + 1/3 | = 0,25
7. (-6/5) + | x-9 |= (-6/5)
8. (-4) . | 3x - 1/5 | = 12
a,-3/7+15/26-(2/13-3/7)
b,2×3/7+(2/9-1 3/7)-5/3:1/9
c,-11/23×6/7+8/7×-11/23-1/23
d,(377/-231-123/89+34/791)×(1/6-1/8-1/24)
Giúp em với ạ , em đag cần gấp...
+) A = ( 1,11 + 0,19 - 2,6 ) : ( 2,06 + 0,54 ) - ( \(\frac{1}{2}\) + \(\frac{1}{3}\) ) : 2
+) Tìm x :
a, (1,16 - x ) . 2,25 / 10 \(\frac{5}{9}\) - 7\(\frac{1}{4}\) . 2\(\frac{2}{11}\) = 75%
b) x + 25% .x = -1,25
c) x - 75% x = \(\frac{1}{4}\)
+) Tính nhanh nếu có thể :
a) 1\(\frac{1}{2}\) - 3\(\frac{3}{4}\) b) -8\(\frac{1}{6}\) - 7\(\frac{3}{2}\) c) 0,15 - 4,8 + 1,3 d) ( 2\(\frac{1}{3}\) + 3,5 ) : (-4\(\frac{1}{6}\) + 3\(\frac{1}{7}\) ) + 7,5
e) 11\(\frac{1}{4}\) + (2\(\frac{5}{7}\) + 5\(\frac{1}{4}\) ) f) \(\frac{4}{9}\) : ( \(\frac{1}{-7}\) + 6\(\frac{5}{9}\) :(-\(\frac{1}{7}\))