Tính B =191/210 + 161/240 + 129 /272 + 95/306
tính tổng
A = 70 .[ 121212/565656 + 121212/727272 + 121212/909090
B = 191/210 + 161/240 +129/272 + 95/306
tính B=191/210+161/240+129/272+95/306
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thanks trước nha!
Bài 1;Cho:
A=\(\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{308}+\dfrac{1}{309}\)
B=\(\dfrac{308}{1}+\dfrac{307}{2}+\dfrac{306}{3}+...+\dfrac{3}{306}+\dfrac{2}{307}+\dfrac{1}{308}\)
Tính \(\dfrac{A}{B}\)
\(A=\dfrac{4}{3}.\dfrac{4}{7}+\dfrac{4}{7}.\dfrac{4}{11}+\dfrac{4}{11}.\dfrac{4}{15}+...+\dfrac{4}{95}.\dfrac{4}{99}\)
Tính \(A=\dfrac{1}{3}.\dfrac{1}{7}+\dfrac{1}{7}.\dfrac{1}{11}+\dfrac{1}{11}.\dfrac{1}{15}+...+\dfrac{1}{95}.\dfrac{1}{99}\)
1. Tính nhanh :
\(\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}\)
2. Tính nhanh :
\(\dfrac{1}{15}+\dfrac{1}{35}+\dfrac{1}{63}+\dfrac{1}{99}+\dfrac{1}{143}\)
3. Tính nhanh :
\(\dfrac{1}{2}+\dfrac{1}{14}+\dfrac{1}{35}+\dfrac{1}{65}+\dfrac{1}{104}+\dfrac{1}{152}\)
4. Chứng minh rằng :
\(\dfrac{1}{2^2}+\dfrac{1}{3^2}+\dfrac{1}{4^2}+...+\dfrac{1}{10^2}\)\(< 1\)
Tìm a,b,c \(\in\)N biết a + b + c = 210; \(\dfrac{6}{7}a=\dfrac{9}{11}b=\dfrac{2}{3}c\)
Tính :
a) b)
\(\dfrac{\dfrac{5}{7}+\dfrac{5}{9}+\dfrac{5}{11}}{\dfrac{25}{7}+\dfrac{25}{7}+\dfrac{25}{11}}\) \(\dfrac{4+\dfrac{4}{73}-\dfrac{4}{115}}{5+\dfrac{5}{73}-\dfrac{1}{23}}\)
Mong mọi người sẽ trả lời nhanh ai nhanh mình sẽ cho 2 like luôn