bài 3:tính giá trị biểu thức
479 – 848 : 4138 : ( 19-16)=
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Lời giải:
$=(\frac{3}{5}+\frac{2}{5})+(\frac{5}{11}+\frac{16}{11})+(\frac{7}{13}+\frac{19}{13})$
$=\frac{5}{5}+\frac{22}{11}=\frac{26}{13}=1+2+2=5$
\(\frac{3}{5}+\frac{5}{1}+\frac{7}{13}\)\(+\frac{2}{5}+\frac{16}{11}+\frac{19}{13}\)
= \(\left(\frac{3}{5}+\frac{2}{5}\right)\)+\(\left(\frac{7}{13}+\frac{19}{13}\right)\)+5 +\(\frac{16}{11}\)
=1+2+5+\(\frac{16}{11}\)
=...
3/5 + 5/1 + 7/13 + 2/5 +16 /11+19/13
= (3/5+2/5)+(5/1+16/11)+(7/13+19/13)
=1+21/11+28/13
bạn tự tính tiếp nhé tiếp theo dễ lắm
Lời giải:
\(\frac{3}{4}\times \frac{8}{9}\times \frac{15}{16}\times ....\times \frac{99}{100}\)
\(=\frac{3\times 8\times 15\times ....\times 99}{4\times 9\times 16\times ....\times 100}\)
\(=\frac{(1\times 3)\times (2\times 4)\times (3\times 5)\times ...\times (9\times 11)}{2\times 2\times 3\times 3\times 4\times 4\times ....\times 10\times 10}\)
\(=\frac{(1\times 2\times 3\times ...\times 9)\times (3\times 4\times 5\times ....\times 11)}{(2\times 3\times 4\times....\times 10)\times (2\times 3\times 4\times ...\times 10)}\)
\(=\frac{1\times 2\times 3\times ....\times 9}{2\times 3\times 4\times ....\times 10}\times \frac{3\times 4\times 5\times ...\times 11}{2\times 3\times 4\times ...\times 10}\)
\(=\frac{1}{10}\times \frac{11}{2}=\frac{11}{20}\)
A=\(2^2-9^3+4^{-2}.16-2.5^2\)
\(=4-729+1-50=-774\)
B=\(\left(2^3.2\right).\dfrac{1}{2}+3^{-2}.3^2-7.1+5\)
\(B=2^4.\dfrac{1}{2}+1-7+5=8+1-7+5=7\)
C = 2-3 + (52)3.5-3 + 4-3.16 - 2.32 - 105.(\(\dfrac{24}{51}\))0
C = \(\dfrac{1}{8}\) + 56.5-3 + 4-3.42 - 2.9 - 105.1
C = \(\dfrac{1}{8}\) + 53 + \(\dfrac{1}{4}\) - 18 - 105
C = (\(\dfrac{1}{8}\) + \(\dfrac{1}{4}\)) - (105 - 125 + 18)
C = \(\dfrac{3}{8}\) - (-20 + 18)
C = \(\dfrac{3}{8}\) + 2
C = \(\dfrac{19}{8}\)
\(M=16\frac{3}{31}-\left(\frac{19}{28}-10\frac{3}{31}\right)\)
\(M=16\frac{3}{31}-\frac{19}{28}-10\frac{3}{31}\)
\(M=\left(16\frac{3}{31}-10\frac{3}{31}\right)-\frac{19}{28}\)
\(M=6-\frac{19}{28}=\frac{149}{28}\)
Bấm Đúng cho mình nhé ! ^^
\(M=\left(16\frac{3}{31}-10\frac{3}{31}\right)-\frac{19}{28}\)
\(M=6-\frac{19}{28}\)
\(M=5\frac{28}{28}-\frac{19}{28}\)
\(M=5\frac{9}{28}\)
\(\left(20^2+18^2+16^2+......+4^2+2^2\right)-\left(19^2+17^2+.....+3^2+1^2\right)\)
\(=20^2-19^2+18^2-17^2+......+2^2-1^2\)
\(=\left(20-19\right)\left(20+19\right)+\left(18-17\right)\left(18+17\right)+.......+\left(2-1\right)\left(2+1\right)\)
\(=39+35+....+7+3\)
\(=\left(39+3\right)\left[\left(39-3\right):4+1\right]:2=210\)
\(=479-\dfrac{424}{6207}=\dfrac{2972729}{6207}\)
479 - 848 : 4138: ( 19-16)
= 479 - 848 : 4138 : 3
= 479 - (0,2049 : 3)
= 479 - 0,0683
=478.9317
đáp số đó nhe nhớ tick cho mình