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a)
6x+70 =570-440
6x+70 =130
6x =130-70
6x =60
x =60:6
x =10
b)^ là mũ nhé!
(2^x+1).2^x=1000+24
(2^x+1).2^x=1024
2^x.2.2^x=1024
2^x.2^x=1024:2=512
2.2^x=512
2^x=512:2=256
2^x=2^8
x=8
\(\frac{3}{5}\cdot\frac{18}{17}+\frac{3}{5}\cdot\frac{9}{17}-\frac{3}{5}\cdot\frac{10}{17}\)
\(=\frac{3}{5}\left[\frac{18}{17}+\frac{9}{17}-\frac{10}{17}\right]\)
\(=\frac{3}{5}\left[\frac{18+9-10}{17}\right]=\frac{3}{5}\cdot1=\frac{3}{5}\)
Bài làm
\(\frac{3}{5}.\frac{18}{17}+\frac{3}{5}.\frac{9}{18}-\frac{3}{5}.\frac{10}{17}\)
\(=\frac{3}{5}.\left(\frac{18}{17}+\frac{9}{18}-\frac{10}{17}\right)\)
~ Đến đây tự tính, tối rồi, lười k mún tính . tính trong ngoặc trc nha~
# Học tốt #
Bài làm
\(A=\frac{2^2.10+2^3.6}{2^2.15-2^4}\)
\(A=\frac{2^2.10+2.2^2.6}{2^2.15-2^2.2^2.1}\)
\(A=\frac{2^2.\left(10+6\right).2}{2^2.\left(15-1\right).2^2}\)
\(A=\frac{2^2.16.2}{2^2.14.2^2}\)
\(A=\frac{16}{14.2}\)
\(A=\frac{8}{7.2}\)
\(A=\frac{8}{14}\)
\(A=\frac{4}{7}\)
Vậy \(A=\frac{4}{7}\)
\(B=\frac{2^9.15^{17}.75^3}{18^8.5^{24}.9^2}\)
\(B=\frac{2^9.\left(3.5\right)^{17}.\left(3.5^2\right)^3}{\left(2.3^2\right)^8.5^{24}.\left(3^2\right)^2}\)
\(B=\frac{2^9.3^{17}.5^{17}.3^3.5^6}{2.3^{19}.5^{24}.3^4}\)
\(B=\frac{2^8.1.1.1.5}{1.3^2.1.3}\)
\(B=\frac{2^8.5}{3^3}\)
\(B=\frac{1280}{27}\)
a)Ta có:
\(\frac{419}{-723}< 0< \frac{-697}{-313}\)
\(\Rightarrow\frac{419}{-723}< \frac{-697}{-313}\)
c)\(\frac{17}{215}>\frac{17}{314}\)
d)Ta có:
\(\frac{11}{54}< \frac{22}{54}< \frac{22}{37}\)
\(\Rightarrow\frac{11}{54}< \frac{22}{37}\)
e)Ta có:
\(\frac{-385}{-126}>0>\frac{-57}{3461}\)
\(\Rightarrow\frac{-385}{-126}>\frac{-57}{3461}\)
f)Ta có:
\(\frac{123}{109}>1>\frac{556}{789}\)
\(\Rightarrow\frac{123}{109}>\frac{556}{789}\)
g)Ta có:
\(\frac{-56}{57}>-1>\frac{-49}{47}\)
\(\Rightarrow\frac{-56}{57}>\frac{-49}{47}\)
\(S=\frac{2016}{2.3:2}+\frac{2016}{3.4:2}+...+\frac{2016}{2015.2016:2}\)
\(S=\frac{4032}{2.3}+\frac{4032}{3.4}+...+\frac{4032}{2015.2016}\)
\(S=4032\left[\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{2015.2016}\right]\)
\(S=4032\left[\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2015}-\frac{1}{2016}\right]\)
\(S=4032\left[\frac{1}{2}-\frac{1}{2016}\right]=4032\cdot\frac{1007}{2016}\)
\(S=2014\)
S = \(2016+\frac{2016}{1+2}+\frac{2016}{1+2+3+}+...+\frac{2016}{1+2+3+...+2015}\)
S = \(2016+\left(\frac{2016}{1+2}+\frac{2016}{1+2+3}+...+\frac{2016}{1+2+3+...+2015}\right)\)
S = \(2016+2016.\left(\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...+2015}\right)\)
đặt A = \(\frac{1}{1+2}+\frac{1}{1+2+3}+...+\frac{1}{1+2+3+...+2015}\)
A = \(\frac{1}{\left(1+2\right).2:2}+\frac{1}{\left(1+3\right).3:2}+...+\frac{1}{\left(1+2015\right).2015:2}\)
A = \(\frac{2}{2.3}+\frac{2}{3.4}+...+\frac{2}{2015.2016}\)
A = \(2.\left(\frac{1}{2}-\frac{1}{3}\right)+2.\left(\frac{1}{3}-\frac{1}{4}\right)+...+2.\left(\frac{1}{2015}-\frac{1}{2016}\right)\)
A = \(2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{2015}-\frac{1}{2016}\right)\)
A = \(2.\left(\frac{1}{2}-\frac{1}{2016}\right)\)
A = \(2.\frac{1007}{2016}=\frac{1007}{1008}\)
Thay A vào ta được :
S = \(2016+2016.\frac{1007}{1008}\)
S = \(2016.\left(1+\frac{1007}{1008}\right)\)
S = \(2016.\frac{2015}{1008}\)
S = \(4030\)