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Lời giải:
a. $=(327-27)+(216-16)+600=300+200+600=1100$
b. $=16\times 48+16\times 24+16\times 28$
$=16\times (48+24+28)=16\times 100=1600$
a) \(\frac{19}{27}+\frac{9}{7}+\frac{6}{27}+\frac{5}{7}+\frac{2}{27}\)
\(=\left(\frac{19}{27}+\frac{6}{27}+\frac{2}{27}\right)+\left(\frac{9}{7}+\frac{5}{7}\right)\)
\(=1+2=3\)
b) \(\frac{2}{7}+\frac{27}{48}+\frac{7}{16}+\frac{45}{63}\)
\(=\frac{2}{7}+\frac{9}{16}+\frac{7}{16}+\frac{5}{7}\)
\(=\left(\frac{2}{7}+\frac{5}{7}\right)+\left(\frac{9}{16}+\frac{7}{16}\right)\)
\(=1+1=2\)
Bài làm:
Ta có: \(A=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+...+\frac{1}{2187}+\frac{1}{6561}=\frac{1}{3}+\frac{1}{3^2}+\frac{1}{3^3}+...+\frac{1}{3^7}+\frac{1}{3^8}\)
=> \(3A=1+\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^6}+\frac{1}{3^7}\)
=> \(3A-A=\left(1+\frac{1}{3}+...+\frac{1}{3^7}\right)-\left(\frac{1}{3}+\frac{1}{3^2}+...+\frac{1}{3^8}\right)\)
<=> \(2A=1-\frac{1}{3^8}=\frac{3^8-1}{3^8}\)
=> \(A=\frac{3^8-1}{3^8.2}\)
Bài làm :
Ta có :
\(A=\frac{1}{3}+\frac{1}{9}+\frac{1}{27}+...+\frac{1}{6561}\)
\(\Rightarrow3\times A=\frac{1\times3}{3}+\frac{1\times3}{9}+\frac{1\times3}{27}+...+\frac{1\times3}{6561}\)
\(3\times A=1+\frac{1}{3}+\frac{1}{9}+...+\frac{1}{729}+\frac{1}{2187}\)
\(3\times A=1+\frac{1}{3}+\frac{1}{9}+...+\frac{1}{729}+\frac{1}{2187}+\left(\frac{1}{6561}-\frac{1}{6561}\right)\)
\(3\times A=1+\left(\frac{1}{3}+\frac{1}{9}+...+\frac{1}{729}+\frac{1}{2187}+\frac{1}{6561}\right)-\frac{1}{6561}\)
\(3\times A=1+A-\frac{1}{6561}\)
\(\Rightarrow2\times A=1-\frac{1}{6561}\)( Trừ bỏ A ở cả 2 vế )
\(2\times A=\frac{6560}{6561}\)
\(A=\frac{6560}{6561}\div2=\frac{3280}{6561}\)
Vậy A=3280/6561
Chúc bạn học tốt !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
53 x 4 x 3 x 25 = 53 x ( 4 x 25 ) x 3
= 53 x 100 x 3
= 15900
327 x 73 + 27 x 327 = 327 x ( 73 + 27 )
= 327 x 100
= 32700
Hok Tốt nhen
a) \(52\times4\times3\times25\)
\(=\left(52\times3\right)\times\left(4\times25\right)\)
\(=156\times100\)
\(=15600\)
b) \(327\times73+27\times327\)
\(=327\left(73+27\right)\)
\(=327\times100\)
\(=32700\)
B , =(5327-247)-(1247-327)
= 5080 - 920
= kết quả tự đi mà tính
a,=2600
b,=622
kmik nha mấy bạn
lm ra từng chi tiết bn nhé