tính giá trị biểu thức: 1+5+5^2+5^3+...+5^17/1+5^2+5^4+5^6+...+5^16
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\(\dfrac{11}{2}\): \(\dfrac{1}{4}\) \(\times\) \(\dfrac{5}{3}\)
= \(\dfrac{11}{2}\) \(\times\) \(\dfrac{4}{1}\) \(\times\) \(\dfrac{5}{3}\)
= 22 \(\times\) \(\dfrac{5}{3}\)
= \(\dfrac{110}{3}\)
\(\dfrac{5}{2}-\dfrac{1}{4}+\dfrac{5}{3}\)
= \(\dfrac{30}{12}-\dfrac{3}{12}+\dfrac{20}{12}\)
= \(\dfrac{7}{12}\)
\(\dfrac{14}{5}\times\dfrac{2}{3}\)+ 5
= \(\dfrac{28}{15}\) + 5
= \(\dfrac{28}{15}\) + \(\dfrac{75}{15}\)
= \(\dfrac{103}{15}\)
Ta có: \(S=\left(5-\frac{2}{3}+\frac{3}{2}\right)-\left(7-\frac{5}{4}-\frac{1}{2}\right)-\left(1-\frac{4}{3}+\frac{2}{5}\right).\)
\(\Rightarrow S=\left(\frac{13}{3}+\frac{3}{2}\right)-\left(\frac{23}{4}-\frac{1}{2}\right)-\left(\frac{-1}{3}+\frac{2}{5}\right)\)
\(\Rightarrow S=\frac{35}{6}-\frac{21}{4}-\frac{1}{15}\)
\(\Rightarrow S=\frac{7}{12}-\frac{1}{15}=\frac{31}{60}\)
Vậy \(S=\frac{31}{60}\)
(1) 5/2 x (3/4 - 1/3) -11/12+1/4 = 5/2 x (9/12-4/12) -11/12 +3/12=5/2 x 5/12 -11/12 +3/12 = 25/24 - 11/12 +3/12=25/24 -22/24 + 6/24=9/12=3/4
(2) 11/12 : (4/10 + 3/5) + (5/6 - 1/2) x2/3
= 11/12 : (4/10 + 6/10) + (5/6-3/6) x 2/3
= 11/12:1 +1/2 x 2/3
= 11/12 + 2/3 =11/12+8/12 = 19/12
\(\dfrac{15}{16}.\dfrac{8}{5}.\dfrac{3}{4}\)= \(\dfrac{5.3.4.2.3}{4.2.2.5.4}=\dfrac{9}{8}\)
= 3/4 + 5/6 x 3/2 + 1/5
= 3/4 + 5/4 + 1/5
= 15/20 + 25/20 + 4/20
= 44/20
= 11/5
TL
\(\frac{3}{4}+\frac{5}{6}:\frac{2}{3}+\frac{1}{5}\)
\(=\frac{3}{4}+\frac{5}{4}+\frac{1}{5}\)
\(=\frac{11}{5}\)
nhaaaaaaa
HT
A = \(\dfrac{1+5+5^2+5^3+5^4+...+5^{17}}{1+5^2+5^4+...+5^{16}}\)
Đặt tử số là B = 1 + 5 + 52 + 53 + 54 +...+ 517
5B = 5 + 52 + 53 + 54 +...+ 517 + 518
5B - B = 518 - 1
4B = 518 - 1
B = (518 - 1) : 4
Đặt mẫu số là C = 1 + 52 + 54 +...+ 516
52.C = 52 + 54 +...+ 516 + 518
25.C - C = 518 - 1
24C = 518 - 1
C = (518 - 1): 24
A = \(\dfrac{B}{C}\) = \(\dfrac{\dfrac{5^{18}-1}{4}}{\dfrac{5^{18}-1}{24}}\)
A = 6
a=6 banj nha