rút gọn
A= 410+84/ 45+ 86
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\(\dfrac{90}{120}=\dfrac{30.3}{30.4}=\dfrac{3}{4}\)
\(\dfrac{15}{25}=\dfrac{5.3}{5.5}=\dfrac{3}{5}\)
\(\dfrac{18}{45}=\dfrac{9.2}{9.5}=\dfrac{2}{5}\)
\(\dfrac{36}{64}=\dfrac{4.9}{4.16}=\dfrac{9}{16}\)
\(\dfrac{32}{72}=\dfrac{8.4}{8.9}=\dfrac{4}{9}\)
\(\dfrac{84}{49}=\dfrac{7.12}{7.7}=\dfrac{12}{7}\)
\(\dfrac{90}{120}=\dfrac{3}{4};\dfrac{15}{25}=\dfrac{3}{5};\dfrac{18}{45}=\dfrac{2}{5};\dfrac{36}{64}=\dfrac{9}{16};\dfrac{32}{72}=\dfrac{4}{9};\dfrac{84}{49}=\dfrac{12}{7}\)
a: \(A=2^{100}-2^{99}+2^{98}-2^{97}+...+2^2-2\)
=>\(2A=2^{101}-2^{100}+2^{99}-2^{98}+...+2^3-2^2\)
=>\(2A+A=2^{101}-2^{100}+2^{99}-2^{98}+...+2^3-2^2+2^{100}-2^{99}+...+2^2-2\)
=>\(3A=2^{101}-2\)
=>\(A=\dfrac{2^{101}-2}{3}\)
b: Sửa đề: \(A=\dfrac{2\cdot8^4\cdot27^2+4\cdot6^9}{2^7\cdot6^7+2^7\cdot40\cdot9^4}\)
\(A=\dfrac{2\cdot2^{12}\cdot3^6+2^2\cdot2^9\cdot3^9}{2^7\cdot2^7\cdot3^7+2^7\cdot2^3\cdot5\cdot3^8}\)
\(=\dfrac{2^{11}\cdot3^6\left(2^3+3^3\right)}{2^{10}\cdot3^7\left(2^4+5\cdot3\right)}\)
\(=\dfrac{2}{3}\cdot\dfrac{4+27}{16+15}=\dfrac{2}{3}\)
c: \(B=\dfrac{4^5\cdot9^4-2\cdot6^4}{2^{10}\cdot3^8+6^8\cdot20}\)
\(=\dfrac{2^{10}\cdot3^8-2\cdot2^4\cdot3^4}{2^{10}\cdot3^8+2^8\cdot2^2\cdot5\cdot3^8}\)
\(=\dfrac{2^5\cdot3^4\left(2^5\cdot3^4-1\right)}{2^{10}\cdot3^8\left(1+5\right)}=\dfrac{1}{2^5\cdot3^4}\cdot\dfrac{32\cdot81-1}{6}\)
\(=\dfrac{2591}{2^6\cdot3^5}\)
\(\dfrac{16}{26}=\dfrac{8}{13};\dfrac{36}{12}=3;\dfrac{48}{86}=\dfrac{16}{13};\dfrac{80}{65}=\dfrac{16}{13}\)
a) \(\frac{6}{9}=\frac{6:3}{9:3}=\frac{2}{3}\)
b)\(\frac{10}{48}=\frac{10:2}{48:2}=\frac{5}{24}\)
c)\(\frac{72}{84}=\frac{72:12}{84:12}=\frac{6}{7}\)
d)\(\frac{1212}{3939}=\frac{1212:303}{3939:303}=\frac{4}{13}\)
#H
Rút gọn phân số:
\(\frac{6}{9}=\frac{6\div3}{9\div3}=\frac{2}{3}\)
\(\frac{10}{48}=\frac{10\div2}{48\div2}=\frac{5}{24}\)
\(\frac{72}{84}=\frac{72\div12}{84\div12}=\frac{6}{7}\)
\(\frac{1212}{3939}=\frac{1212\div303}{3939\div303}=\frac{4}{13}\)
a: 90/126=5/7<6/7
b: 70/84=5/6
35/42=5/6
=>70/84=35/42
(√28 - 2√3 + √7)√7 + √84
= (√4.7 - 2√3 + √7)√7 + √4.21
= (2√7 - 2√3 + √7)√7 + 2√21
= (3√7 - 2√3)√7 + 2√21
= 3.7 - 2√21 + 2√21 = 21
\(\frac{12}{84}+\frac{36}{63}\)
\(=\frac{1}{7}+\frac{4}{7}=\frac{5}{7}\)
học tốt ~~~
\(\frac{12}{84}=\frac{1}{4}\)
\(\frac{36}{63}=\frac{4}{7}\)
Ta có :
\(\frac{1}{4}=1-\frac{3}{4}\)
\(\frac{4}{7}=1-\frac{3}{7}\)
Mà \(\frac{3}{4}>\frac{3}{7}\) nên \(\frac{1}{4}< \frac{4}{7}\)
\(\Rightarrow\) \(\frac{12}{84}< \frac{36}{63}\) .
4^5/8^2
Ta có
A=410+84/45+86
A=410+23.4/22.5+86
A=410+212/210+86
A=410+22+86
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