C = 1/21+1/77+1/165+1/285+1/437+1/621
chứng tỏ C < 4/27
Những câu hỏi liên quan
B=1/21+1/77+1/165+1/285+1/437+1/621
Tính A biết :\(A=\frac{1}{21}+\frac{1}{77}+\frac{1}{165}+\frac{1}{285}+\frac{1}{437}\)
A = \(\frac{1}{21}+\frac{1}{77}+\frac{1}{165}+\frac{1}{285}+\frac{1}{437}\)
A = \(\frac{1}{3.7}+\frac{1}{7.11}+\frac{1}{11.15}+\frac{1}{15.19}+\frac{1}{19.23}\)
A = \(\frac{1}{4}.\left(\frac{1}{3}-\frac{1}{7}\right)+\frac{1}{4}.\left(\frac{1}{7}-\frac{1}{11}\right)+\frac{1}{4}.\left(\frac{1}{11}-\frac{1}{15}\right)+\frac{1}{4}.\left(\frac{1}{15}-\frac{1}{19}\right)+\frac{1}{4}.\left(\frac{1}{19}-\frac{1}{23}\right)\)
A = \(\frac{1}{4}.\left(\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}+\frac{1}{19}-\frac{1}{23}\right)\)
A = \(\frac{1}{4}.\left(\frac{1}{3}-\frac{1}{23}\right)\)
A = \(\frac{1}{4}.\frac{20}{69}\)
A = \(\frac{5}{69}\)
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Tính hợp lí: a) A dfrac{1}{56} + dfrac{1}{72} + dfrac{1}{90} + dfrac{1}{110} + dfrac{1}{132} + dfrac{1}{156} ; b) B dfrac{4}{21} + dfrac{4}{77} + dfrac{4}{165} + dfrac{4}{285} +dfrac{4}{437} +dfrac{4}{621}; c) C dfrac{1}{21} + dfrac{1}{77} +dfrac{1}{165} +dfrac{1}{285} +dfrac{1}{437} +dfrac{1}{621} ; d) D dfrac{1}{1.6} + dfrac{1}{6.11} +dfrac{1}{11.16} +dfrac{1}{16.21} +dfrac{1}{26.31} .
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Tính hợp lí:
a) A = \(\dfrac{1}{56}\) + \(\dfrac{1}{72}\) + \(\dfrac{1}{90}\) + \(\dfrac{1}{110}\) + \(\dfrac{1}{132}\) + \(\dfrac{1}{156}\) ;
b) B = \(\dfrac{4}{21}\) + \(\dfrac{4}{77}\) + \(\dfrac{4}{165}\) + \(\dfrac{4}{285}\) +\(\dfrac{4}{437}\) +\(\dfrac{4}{621}\);
c) C = \(\dfrac{1}{21}\) + \(\dfrac{1}{77}\) +\(\dfrac{1}{165}\) +\(\dfrac{1}{285}\) +\(\dfrac{1}{437}\) +\(\dfrac{1}{621}\) ;
d) D = \(\dfrac{1}{1.6}\) + \(\dfrac{1}{6.11}\) +\(\dfrac{1}{11.16}\) +\(\dfrac{1}{16.21}\) +\(\dfrac{1}{26.31}\) .
Giải:
a)A=1/56+1/72+1/90+1/110+1/132+1/156
A=1/7.8+1/8.9+1/9.10+1/10.11+1/11.12+1/12.13
A=1/7-1/8+1/8-1/9+1/9-1/10+1/10-1/11+1/11-1/12+1/12-1/13
A=1/7-1/13
A=6/91
b)B=4/21+4/77+4/165+4/285+4/437+4/621
B=4/3.7+4/7.11+4/11.15+4/15.19+4/19.23+4/23.27
B=1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27
B=1/3-1/27
B=8/27
c) C=1/21+1/77+1/165+1/285+1/437+1/621
C=1/3.7+1/7.11+1/11.15+1/15.19+1/19.23+1/23.27
C=1/4.(4/3.7+4/7.11+4/11.15+4/15.19+4/19.23+4/23.27)
C=1/4.(1/3-1/7+1/7-1/11+1/11-1/15+1/15-1/19+1/19-1/23+1/23-1/27)
C=1/4.(1/3-1/27)
C=1/4.8/27
C=2/27
d) D=1/1.6+1/6.11+1/11.16+1/16.21+1/21.26+1/26.31
D=1/5.(5/1.6+5/6.11+5/11.16+5/16.21+5/21.26+5/26.31)
D=1/5.(1/1-1/6+1/6-1/11+1/11-1/16+1/16-1/21+1/21-1/26+1/26-1/31)
D=1/5.(1/1-1/31)
D=1/5.30/31
D=6/31
Nếu câu d cậu viết thiếu thì làm như vầy nhé!
Chúc bạn học tốt!
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Nếu như câu d ko chép sai thì làm thế này nha:
d) D=1/1.6+1/6.11+1/11.16+1/16.21+1/26.31
D=1/5.(5/1.6+5/6.11+5/11.16+5/16.21)+1/806
D=1/5.(1/1-1/6+1/6-1/11+1/11-1/16+1/16-1/21)+1/806
D=1/5.(1/1-1/21)+1/806
D=1/5.20/21+1/806
D=4/21+1/806
D=3245/16926
Chúc bạn học tốt!
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\(D=\frac{4}{21}+\frac{4}{77}+\frac{4}{165}+\frac{4}{285}+\frac{4}{437}+\frac{4}{621}\)
\(D=\frac{4}{21}+\frac{4}{77}+\frac{4}{165}+\frac{4}{285}+\frac{4}{437}+\frac{4}{621}\)
\(D=\frac{4}{3.7}+\frac{4}{7.11}+\frac{4}{11.15}+\frac{4}{15.19}+\frac{4}{19.23}+\frac{4}{23.27}\)
\(D=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}+\frac{1}{19}-\frac{1}{23}+\frac{1}{23}-\frac{1}{27}\)
\(D=\frac{1}{3}-\frac{1}{27}\)
\(D=\frac{9}{27}-\frac{1}{27}\)
\(D=\frac{8}{27}\)
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\(D=\frac{4}{21}+\frac{4}{77}+\frac{4}{165}+\frac{4}{285}+\frac{4}{437}+\frac{4}{621}\)
\(D=\frac{4}{3.7}+\frac{4}{7.11}+\frac{4}{11.15}+\frac{4}{15.19}+\frac{4}{19.23}+\frac{4}{23.27}\)
\(D=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{15}+\frac{1}{15}-\frac{1}{19}+\frac{1}{19}-\frac{1}{23}+\frac{1}{23}-\frac{1}{27}\)
\(D=\frac{1}{3}-\frac{1}{27}\)
\(D=\frac{8}{27}\)
_Chúc bạn học tốt_
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D= 4/21 + 4/77 + 4/165 + 4/285 + 4/437 + 4/621
D= 4/3.7 + 4/7.11 + 4/11.15 + 4/15.19 + 4/19.23 + 4/23.27
D= 1/3 - 1/7 + 1/7 -1/11 +1/11 -1/15 +1/15 -1/19 +1/19 -1/23 +1/23 -1/27
D= 1/3 - 1/27
D=9/27 - 1/27
D=8/27
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Xem thêm câu trả lời
tính giá trị biểu thứcAfrac{-378.132+189.64}{15+18+21+......+45+48}B1,4.frac{15}{14}-left(frac{4}{5}+frac{2}{5}right):2frac{1}{5}-frac{frac{73}{77}+frac{73}{165}+frac{73}{285}}{frac{25}{24}+frac{15}{180}+frac{20}{285}}Cfrac{7+frac{7}{12}-frac{7}{144}+frac{7}{60}}{5+frac{6}{12}-frac{5}{144}}.frac{frac{3}{4}-frac{3}{16}+frac{3}{64}-frac{3}{256}}{1-frac{1}{4}+frac{1}{16}-frac{1}{34}}-frac{1}{20}
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tính giá trị biểu thức
\(A=\frac{-378.132+189.64}{15+18+21+......+45+48}\)
\(B=1,4.\frac{15}{14}-\left(\frac{4}{5}+\frac{2}{5}\right):2\frac{1}{5}-\frac{\frac{73}{77}+\frac{73}{165}+\frac{73}{285}}{\frac{25}{24}+\frac{15}{180}+\frac{20}{285}}\)
\(C=\frac{7+\frac{7}{12}-\frac{7}{144}+\frac{7}{60}}{5+\frac{6}{12}-\frac{5}{144}}.\frac{\frac{3}{4}-\frac{3}{16}+\frac{3}{64}-\frac{3}{256}}{1-\frac{1}{4}+\frac{1}{16}-\frac{1}{34}}-\frac{1}{20}\)
Tính :
6/21 + 6/77 + 6/165 + 6/285
giúp mình với
người nào làm xong đầu tiên mình sẽ cho 1 like cho người đó.
Bài 1:Thực hiện phép tính sau:
(4/77+4/165+4/285):(5/84+3/180+4/285)
Bài 2:Tìm x:
(x+2/3).-3/5+4/7-11/7x
Tính nhanh:
A=10 - 1/72 - 1/50 - 1/42- .... - 1/6 - 1/2
Tìm x:
a.(x+1) + (x+1/3) +(x+1/6) +...+(x+1/55)= 130/11
b. 2/3.x - 780/11 :(13/15 +13/3535+13/63+1313/9999) +5=0
c. 2012/77 +20112/165 +2012/258 +2012/437=16/161 .x
Cảm ơn nhiều!!!!!!!!!!!
Mấy bn ơi, giúp mk vs
Tìm x, biết:
\(x-0,27=\frac{\frac{73}{77}+\frac{73}{165}+\frac{73}{285}}{25\times\left(\frac{5}{84}+\frac{3}{180}+\frac{4}{285}\right)}\)
Tính P;
\(P=\frac{\left(13\frac{1}{4}-2\frac{5}{27}-10\frac{5}{6}\right)\times230\frac{1}{25}+46\frac{3}{4}}{\left(1\frac{3}{7}+\frac{10}{3}\right)\div\left(12\frac{1}{3}-14\frac{2}{7}\right)}\)
Ai đúng mk tích, cảm ơn các bn
Tìm x :
x - 0,27 = \(\frac{73}{100}\)
x = \(\frac{73}{100}+0,27\)
x = 1
Cậu P khó quá mik chưa nghĩ ra cách tính nhanh nhất !
Cậu tự giải nhé !
Hok tốt
\(x-0,27=\frac{\frac{73}{77}+\frac{73}{165}+\frac{73}{285}}{25\times\left(\frac{5}{84}+\frac{3}{180}+\frac{4}{285}\right)}.\)
\(x-0,27=\frac{\frac{146}{105}+\frac{73}{285}}{25\times\left(\frac{8}{105}+\frac{4}{285}\right)}\)
\(x-0,27=\frac{\frac{219}{133}}{25\times\frac{12}{133}}\)
\(x-0,27=\frac{\frac{219}{133}}{\frac{300}{133}}\)
\(x-0,27=0,73\)
\(x=0,73+0,27\)
\(x=1\)
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