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a, 61.49+27.49+12.49+100.51 = 49.(61+27+12)+100.51 = 49.100+51.100 = 100.(49+51) = 100.100 = 10000
b, 2 3 . 3 3 . 5 + 9 . 6 3 - 8 . 6 3 . 2018 0 (để kết quả dưới dạng lũy thừa)
= 6 3 . 5 + 6 3 . 9 - 8 . 6 3 . 1 = 6 3 . ( 5 + 9 - 8 ) = 6 4
c, 25.5.4.27.2 = (25.4).(5.2).27 = 100.10.27 = 27000
d, 12:{400:[500 – (125+25.7)]} = 12:{400:[500 – 300]} = 12:(400:200) = 12:2 = 6
e, 3 2 . 4 2 . 7 + 12 2 . 6 - 6 2 . 2 2 . 13 + 2020 0
= 12 2 . 7 + 12 2 . 6 - 12 2 . 3 + 1
= 12 2 . 7 + 6 - 13 + 1 = 1
a) \(\left(7200+36\right):36\)
\(=7200:36+36:36\)
\(=36\cdot200:36+1\)
\(=201\)
b) \(\left(3600-84\right):12\)
\(=12\cdot300:12-84:12\)
\(=293\)
\(A=\frac{36}{1.3.5}+\frac{36}{3.5.7}+\frac{36}{5.7.9}+.....+\frac{36}{25.27.29}\)
\(=9\left(\frac{4}{3.\left(1.5\right)}+\frac{4}{5\left(3.7\right)}+\frac{4}{7.\left(5.9\right)}+.....+\frac{4}{27\left(25.29\right)}\right)\)
\(=9\left(\frac{1}{3}\left(1-\frac{1}{5}\right)+\frac{1}{5}\left(\frac{1}{3}-\frac{1}{7}\right)+\frac{1}{7}\left(\frac{1}{5}-\frac{1}{9}\right)+...+\frac{1}{27}\left(\frac{1}{25}-\frac{1}{29}\right)\right)\)
\(=9\left(\frac{1}{3}-\frac{1}{3.5}+\frac{1}{5.3}-\frac{1}{5.7}+\frac{1}{7.5}-\frac{1}{7.9}+...+\frac{1}{27.25}-\frac{1}{27.29}\right)\)
\(=9\left(\frac{1}{3}-\frac{1}{27.29}\right)< 9.\frac{1}{3}=3\)
Vậy A < 3.
Phương trình nào biểu diễn 36 nhỏ hơn một số, y, bằng 13?
A. y - 36 = 13
B. 36 - y = 13
C. 13 - y = 36
D. 36 + y = –13
a)\(A=\frac{36}{1.3.5}+\frac{36}{3.5.7}+\frac{36}{5.7.9}+...+\frac{36}{25.27.29}\)
=\(\frac{9.4}{1.3.5}+\frac{9.4}{3.5.7}+\frac{9.4}{5.7.9}+...+\frac{9.4}{25.27.29}\)
=\(9.\left(\frac{4}{1.3.5}+\frac{4}{3.5.7}+\frac{4}{5.7.9}+...+\frac{4}{25.27.29}\right)\)
=\(9.\left(\frac{1}{1.3}-\frac{1}{3.5}+\frac{1}{3.5}-\frac{1}{5.7}+\frac{1}{5.7}-\frac{1}{7.9}+...+\frac{1}{25.27}-\frac{1}{27.29}\right)\)
=\(9.\left(\frac{1}{3}-\frac{1}{27.29}\right)=9.\left(\frac{1}{3}-\frac{1}{783}\right)=9.\left(\frac{261}{783}-\frac{1}{783}\right)=9.\frac{260}{783}\)
=\(\frac{260}{87}\)
b)
ta có: \(3=\frac{261}{87}>\frac{260}{87}\)
vậy A<3
ƯC(26,36)
Ta có
26=2x13
36=2^2x3^
ƯCLN(25,36)=2
ƯC(26,36)=Ư(2){1;2}
BC(26,36)
Ta có 468
26=2x13
36=2^2x3^2
BCNN(26,36)=2^2x3^2x13=4x9x13=468
BC(26,36)=B(26,36)={0;468;936...}
a)=49x(27+61+12)+100x51
=49x100+5100
=4900+5100
=10000
b)=7236:36
=201
k nha p
238,61
201