\(A=\dfrac{8056}{2012.16-1982}\)
\(A=\dfrac{8056}{32192-1982}\)
\(A=\dfrac{8056}{30210}=\dfrac{12}{45}\)
\(B=\dfrac{1.2.6+2.4.12+4.8.24+7.14.42}{1.6.9+2.12.18+4.24.36+7.42.63}\)
\(B=\dfrac{12+96+768+4116}{54+432+3456+18522}\)
\(B=\dfrac{4992}{22464}=\dfrac{10}{45}\)
Vậy: \(\dfrac{12}{45}>\dfrac{10}{45}\Rightarrow A>B\)
1)A=\(\dfrac{5}{1\cdot2}+\dfrac{5}{2\cdot3}+.....+\dfrac{5}{99\cdot100}\)
C=\(1\cdot2\cdot3+2\cdot3\cdot4++3\cdot4\cdot5+4\cdot5\cdot6+5\cdot6\cdot7+6\cdot7\cdot8+7\cdot8\cdot9+8\cdot9\cdot10\)
D=\(1^2+2^2+3^2+...+99^2+100^2\)
tính
\(\frac{5\cdot4^{15}\cdot9^9-4\cdot3^{20}\cdot8^9}{5\cdot2^{10}\cdot6^{19}-7\cdot2^{29}\cdot27^6}\)
Tính: \(\frac{5^2\cdot6^{11}\cdot16^2+6^2\cdot12^6\cdot15^2}{2\cdot6^{12}\cdot10^4-81^2\cdot960^3}\)
3)Rút gọn
\(\dfrac{1\cdot3\cdot5+2\cdot6\cdot10+\text{4*12*20+7*21*35}}{1\cdot5\cdot7+2\cdot10\cdot14+4\cdot20\cdot28+7\cdot35\cdot49}\)
Bài 1: Tìm x biết
\(\dfrac{1}{1\cdot4}+\dfrac{1}{4\cdot7}+\dfrac{1}{7\cdot10}+\dfrac{1}{13\cdot16}\cdot x=\dfrac{3}{8}\)
Bài 2: Tìm các phân số có mẫu là 20 lớn hơn \(\dfrac{7}{15}\) nhỏ hơn \(\dfrac{8}{15}\)
Bài 3: So sánh A và B
A = \(\dfrac{2}{537}+\dfrac{4}{541}\) B = \(\dfrac{2}{541}+\dfrac{4}{537}\)
\(B=5\dfrac{9}{10}:\dfrac{3}{2}-\left(2\dfrac{1}{3}\cdot4\dfrac{1}{2}-2\cdot2\dfrac{1}{3}\right):\dfrac{7}{4}\)
Bài 2
a) \(\dfrac{2^{19}\cdot27^3+15\cdot4^9\cdot9^4}{6^9\cdot2^{10}+12^{10}}\)
a) Tìm số tự nhiên x biết : \(\left(\dfrac{1}{1\cdot2\cdot3}+\dfrac{1}{2\cdot3\cdot4}+...+\dfrac{1}{8\cdot9\cdot10}\right)\cdot x=\dfrac{23}{45}\)
b) Tìm các số tự nhiên a ; b; c ; d biết : \(\dfrac{30}{43}=\dfrac{1}{a+\dfrac{1}{b+\dfrac{1}{c+\dfrac{1}{d}}}}\)
Bài 1. Chứng tỏ rằng: B=\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+\dfrac{1}{5^2}+\dfrac{1}{6^2}+\dfrac{1}{7^2}+\dfrac{1}{8^2}< 1\)
Bài 2. so sánh : A=\(\dfrac{2011+2012}{2012+2013}\)
và B=\(\dfrac{2011}{2012}+\dfrac{2012}{2013}\)
Bài 3. Rút gọn : B= \(\left(1-\dfrac{1}{1}\right).\left(1-\dfrac{1}{3}\right).\left(1-\dfrac{1}{4}\right)...\left(1-\dfrac{1}{20}\right)\)
Bài 4. Rút gọn biểu thức : A= \(1+\dfrac{1}{2}+\dfrac{1}{2^2}+\dfrac{1}{2^3}+...+\dfrac{1}{2^{2012}}\)
Bài 5. Tìm số nguyên \(\pi\) sao cho \(\pi+5\) chia hết cho \(\pi-2\)
HELP ME!!!! MÌNH TICK CHO HA
