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Bài 3 :
A = 26 + 27 + 28 + 29 + 30 + 31 + 32 + 33
=> A = ( 33 + 26 ) . 8 : 2 = 236
Vậy A = 236
\(\text{#Hok tốt!}\)
a) 2 . 31 . 12 + 4 . 6 . 42 + 8 . 27 . 3
= 24 . 31 + 24 . 42 + 24 . 27
= 24 . ( 31 + 42 + 27 )
= 24 . 100
= 2400
Trả lời
b)(1/3+12/67+13/41)-(79/67-28/41)
=1/3+12/67+13/41-79/67+28/41
=1/3+(12/67-79/67)+(13/41+28/41)
=1/3+(-67/67)+41/41
=1/3+(-1)+1
=1/3+0
=1/3.
a, \(B=\frac{19^{31}+5}{19^{32}+5}< \frac{19^{31}+5+90}{19^{32}+5+90}=\frac{19^{31}+95}{19^{32}+95}=\frac{19\left(19^{30}+5\right)}{19\left(19^{31}+5\right)}=\frac{19^{30}+5}{19^{31}+5}=A\)
b, Ta có: \(\frac{1}{A}=\frac{2^{20}-3}{2^{18}-3}=\frac{2^2.\left(2^{18}-3\right)+9}{2^{18}-3}=4+\frac{9}{2^{18}-3}\)
\(\frac{1}{B}=\frac{2^{22}-3}{2^{20}-3}=\frac{2^2\left(2^{20}-3\right)+9}{2^{20}-3}=4+\frac{9}{2^{20}-3}\)
Vì \(\frac{9}{2^{18}-3}>\frac{9}{2^{20}-3}\)\(\Rightarrow\frac{1}{A}>\frac{1}{B}\Rightarrow A< B\)
c, Câu hỏi của truong nguyen kim
\(a.\frac{27.45+27.55}{2+4+6+...+14+16+18}=\frac{27.100}{\frac{\left(2+18\right).9}{2}}=30\)
\(b.\frac{26.108-26.12}{32-28+24-20+16-12+8-4}=\frac{26\left(108-12\right)}{\left(32-28\right).4}=\frac{26.96}{4.4}=156\)
\(c.\frac{27.4500+135.550.2}{2+4+6+...+14+16+18}=\frac{270.450+270.550}{\frac{\left(2+8\right).9}{2}}\)
\(d.\frac{48.700-24.45.20}{45-40+35-30+25-20+15-10+5}=\frac{48.700-48.450}{5.5}\)\(=\frac{48\left(700-450\right)}{25}=\frac{48.250}{25}=480\)
#ĐinhBa
a,
\(\left(20+9\dfrac{1}{4}\right):2\dfrac{1}{4}=\left(20+\dfrac{37}{4}\right):\dfrac{9}{4}\\ =\dfrac{117}{4}\cdot\dfrac{4}{9}\\ =\dfrac{117}{9}=13\)
b,
\(\left(6-2\dfrac{4}{5}\right)\cdot3\dfrac{1}{8}-1\dfrac{3}{5}:\dfrac{1}{4}\\ =\left(6-\dfrac{14}{5}\right)\cdot\dfrac{25}{8}-\dfrac{8}{5}\cdot4\\ =\dfrac{16}{5}\cdot\dfrac{25}{8}-\dfrac{32}{5}\\ =10-\dfrac{32}{5}\\ =\dfrac{18}{5}\)
c,
\(\dfrac{32}{15}:\left(-1\dfrac{1}{5}+1\dfrac{1}{3}\right)\\ =\dfrac{32}{5}:\left(-\dfrac{6}{5}+\dfrac{4}{3}\right)\\ =\dfrac{32}{5}:\dfrac{2}{15}\\ =\dfrac{32}{5}\cdot\dfrac{15}{2}\\ =48\)
a, ( 20 + \(9\dfrac{1}{4}\) ) : \(2\dfrac{1}{4}\)
= ( 20 + \(\dfrac{37}{4}\) ) : \(\dfrac{9}{4}\)
= ( \(\dfrac{80}{4}\) + \(\dfrac{37}{4}\) ) . \(\dfrac{4}{9}\)
= \(\dfrac{117}{4}\) . \(\dfrac{4}{9}\)
= \(\dfrac{117}{9}\) = 13
b, ( 6 - \(2\dfrac{4}{5}\) ) . \(3\dfrac{1}{8}\) - \(1\dfrac{3}{5}\) : \(\dfrac{1}{4}\)
= ( 6 - \(\dfrac{14}{5}\) ) . \(\dfrac{25}{8}\) - \(\dfrac{8}{5}\) . 4
= ( \(\dfrac{30}{5}\) - \(\dfrac{14}{5}\) ) . \(\dfrac{25}{8}\) - \(\dfrac{8}{5}\) . 4
= \(\dfrac{16}{5}\) . \(\dfrac{25}{8}\) - \(\dfrac{8}{5}\). 4
= 10 - \(\dfrac{32}{5}\)
= \(\dfrac{50}{5}\) - \(\dfrac{32}{5}\)
= \(\dfrac{18}{5}\)
c, \(\dfrac{32}{15}\) : ( -\(1\dfrac{1}{5}\) + \(1\dfrac{1}{3}\) )
= \(\dfrac{32}{15}\) : ( \(\dfrac{-6}{5}\) + \(\dfrac{4}{3}\) )
= \(\dfrac{32}{15}\) : ( \(\dfrac{-18}{15}\) + \(\dfrac{20}{15}\) )
= \(\dfrac{32}{15}\) : \(\dfrac{2}{15}\)
= \(\dfrac{32}{15}\) . \(\dfrac{15}{2}\)
= 16
a) 961
b) 10
c) 256
d) 29