\(\frac{36\times36-2}{2+34\times38}\)
A =\(\frac{1}{1\times2\times3}\)+\(\frac{1}{2\times3\times4}\)+\(\frac{1}{3\times4\times5}\)+........+\(\frac{1}{36\times37\times38}\)+\(\frac{1}{37\times38\times39}\) GIÚP MK VỚI MK CẦN GẤP
Vũ Thị Yến Đan
em chịu khó gõ link này lên google
https://olm.vn/hoi-dap/detail/8190810701.html
tham khảo bài của bạn Hoàng Xuân Ngân nhé
Tính D=\(\frac{\frac{15}{6\times16}+\frac{15}{16\times26}+\frac{15}{26\times36}}{\frac{33}{6\times16}-\frac{63}{16\times26}+\frac{93}{26\times36}}\)
Ta có: \(D=\frac{\frac{15}{6x16}+\frac{15}{16x26}+\frac{15}{26x36}}{\frac{33}{6x16}-\frac{63}{16x26}+\frac{93}{26x36}}\)
\(\Rightarrow D=\frac{15.\frac{1}{6x16}+15.\frac{1}{16x26}+15.\frac{1}{26x36}}{3.11.\frac{1}{6x16}-3.21.\frac{1}{16x26}+3.31.\frac{1}{26x36}}\)
\(\Rightarrow D=\frac{15.\left(\frac{1}{6x16}+\frac{1}{16x26}+\frac{1}{26x36}\right)}{3.\left(\frac{11}{6x16}-\frac{21}{16x26}+\frac{31}{26x36}\right)}\)
\(\Rightarrow D=5.\left(\frac{1}{6x16}+\frac{1}{16x26}+\frac{1}{26x36}\right):\left(\frac{11}{6x16}-\frac{21}{16x26}+\frac{31}{26x36}\right)\)
1) Tính nhanh
\(\left(36\times28+45\times36\right):73\)
(36x28+45x36):73
=(36x45+28):73
=(36x73):73
Vi 36x73 rồi lại chia cho 73 thì nó vẫn chính bằng 36
\(\left(36\times28+45\times36\right):73\)
\(=\left(36\times\left(45+28\right)\right):73\)
\(=\left(36\times73\right):73\)
\(=36\times73:73=36\)
\(\left(36\times28+45\times36\right):72\)
\(=\left[36\times\left(28+45\right)\right]:73\)
\(=\left(36\times73\right):73\)
\(=36\times\left(73:73\right)\)
\(=36\times1=36\)
cho : \(M=\frac{1}{1\times2}+\frac{1}{3\times4}+...+\frac{1}{37\times38}\)
và \(N=\frac{1}{20\times38}+\frac{1}{21\times37}+...+\frac{1}{38\times20}\)
Chứng minh : \(\frac{M}{N}\)là số nguyên
Tính hợp lí:
A=\(\frac{5}{12\times17}+\frac{35}{17\times18}-\frac{39}{18\times21}+\frac{30}{21\times72}\)
B=\(\frac{767676\times31-626262\times38}{1^2+2^3+3^4+......+99^{100}}\)
Tính nhanh :
\(\frac{2}{2\times3\times4}\)+ \(\frac{2}{3\times4\times5}\)+ .... \(\frac{2}{37\times38\times39}\)+ \(\frac{2}{38\times39\times40}\)
Giúc mk nhé
=2/2 - 2/3 - 2/4 - .........- 2/38 - 2/39 - 2/40
= 2/2 - 2/40
=1 - 2/40
=38/40
= 19/20
mk ko hiểu cho lắm bn có thể giải thích rõ hơn ko ?
\(=\frac{2}{2}-\frac{2}{3}-\frac{2}{4}-...-\frac{2}{38}-\frac{2}{39}-\frac{2}{40}\)
\(=\frac{2}{2}-\frac{2}{40}\)
\(=1-\frac{2}{40}\)
\(=\frac{38}{40}=\frac{19}{20}\)
Code : Breacker
Tính bằng cách thuận tiện :
a) \(20,18\times36+63\times20,18+20,18\)
Tìm phân số \(\frac{a}{b}\)biết : \(\frac{a}{b}\times\frac{3}{5}=\frac{1}{5}+\frac{2}{3}\)
a) 20,18 x 36 + 63 x 20,18 + 20,18
= 20,18 x ( 36+63+1)
= 20,18 x 100
= 2018
b) \(\frac{a}{b}\times\frac{3}{5}=\frac{1}{5}+\frac{2}{3}\)
\(\frac{a}{b}\times\frac{3}{5}=\frac{13}{15}\)
\(\frac{a}{b}=\frac{13}{15}:\frac{3}{5}\)
\(\frac{a}{b}=\frac{13}{9}\)
a) 20,18.(36+63+1)
= 20,18 . 100
= 2018
a/b . 3/5 =3/15 + 10/15
a/b . 3/5 =13/15
a/b = 13/15 : 3/5
a/b = 13/9
Tính bằng cách thuận tiện :
\(20,18\times36+63\times20,18+20,18\)
\(=\left(36+63+1\right)\times20,18\)
\(=100\times20,18\)
\(=2018\)
Tìm phân số \(\frac{a}{b}\)biết : \(\frac{a}{b}\times\frac{3}{5}=\frac{1}{5}+\frac{2}{3}\)
\(\frac{a}{b}\times\frac{3}{5}=\frac{1}{5}+\frac{2}{3}\)
\(\frac{a}{b}\times\frac{3}{5}=\frac{13}{15}\)
\(\frac{a}{b}=\frac{13}{15}\div\frac{3}{5}\)
\(\frac{a}{b}=\frac{13}{9}\)
~ Study Well ~
a,\(\frac{15}{34}\)+\(\frac{7}{21}\)+\(\frac{19}{34}\)-\(\frac{36}{21}\)+\(\frac{2}{3}\)
Ta có: \(\frac{15}{34}+\frac{7}{21}+\frac{19}{34}-\frac{36}{21}+\frac{2}{3}\)
\(=\frac{15}{34}+\frac{19}{34}+\frac{7}{21}-\frac{36}{21}+\frac{2}{3}\)
\(=1-\frac{29}{31}+\frac{2}{3}=\frac{2}{31}+\frac{2}{3}=\frac{68}{93}\)
\(\frac{64\times50\times44\times100}{27\times38\times146\times19}\)
nhìu dợ chi bằng bấm máy hay hơn đó