a,-15,5 . 20,8 + 2,5 . 92 - 15,5 . 9,2 + 3,5 .20,8
b, (-3/4 + 5/13) : 2/7 - (9/4 - 8/13):2/7
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a) \(\left|2x+1\right|=\left|x+4\right|\Rightarrow\left[{}\begin{matrix}2x+1=x+4\\2x+1=-x-4\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\3x=-5\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=3\\x=-\dfrac{5}{3}\end{matrix}\right.\)
b) \(\left|2x-1\right|=x+4\Rightarrow\left[{}\begin{matrix}2x-1=x+4\\2x-1=-x-4\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=3\\3x=-3\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=3\\x=-1\end{matrix}\right.\)
a: 200<314
=>1/200>1/314
=>17/200>17/314
b: 11/54=22/108
37<108
=>22/37>22/108
=>22/37>11/54
c: 141/893=3/19
159/901=3/17
mà 3/19<3/17
nên 141/893<159/901
d: 9/382=18/764=90/3820
6/257=18/771=90/3855
15/643=90/3858
3820<3855<3858
=>90/3820>90/3855>90/3858
=>9/382>6/257>15/643
a: 200<314
=>1/200>1/314
=>17/200>17/314
b: 11/54=22/108
37<108
=>22/37>22/108
=>22/37>11/54
c: 141/893=3/19
159/901=3/17
mà 3/19<3/17
nên 141/893<159/901
d: 9/382=18/764=90/3820
6/257=18/771=90/3855
15/643=90/3858
3820<3855<3858
=>90/3820>90/3855>90/3858
=>9/382>6/257>15/643
13:
Qua G, kẻ mn//a//b
mn//a
=>góc G1=góc A1(hai góc so le trong)
=>góc G1=42 độ
mn//b
=>góc G2+góc B2=180 độ(trong cùng phía)
=>góc G2=180-138=42 độ
=>góc AGB=42+42=84 độ
`@` `\text {Ans}`
`\downarrow`
`32^x \div 16^x = 128`
`=> (2^5)^x \div (2^4)^x = 2^7`
`=> 2^(5x) \div 2^(4x) = 2^7`
`=> 2^(5x - 4x) = 2^7`
`=> 2^x = 2^7`
`=> x = 7`
Vậy, `x = 7.`
\(x^{10}=x\)
\(\Rightarrow x^{10}-x=0\)
\(\Rightarrow x\left(x^9-1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x^9-1=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x^9=1\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=0\\x=1\end{matrix}\right.\)
a) Ta có :
\(27^{27}>27^{26}=\left(27^2\right)^{13}=729^{13}>243^{13}\)
\(\Rightarrow27^{27}>243^{13}\)
\(\Rightarrow-27^{27}< -243^{13}\)
\(\Rightarrow\left(-27\right)^{27}< \left(-243\right)^{13}\)
b) \(\left(\dfrac{1}{8}\right)^{25}>\left(\dfrac{1}{8}\right)^{26}=\left(\dfrac{1}{8^2}\right)^{13}=\left(\dfrac{1}{64}\right)^{13}>\left(\dfrac{1}{128}\right)^{13}\)
\(\Rightarrow\left(\dfrac{1}{8}\right)^{25}>\left(\dfrac{1}{128}\right)^{13}\)
\(\Rightarrow\left(-\dfrac{1}{8}\right)^{25}< \left(-\dfrac{1}{128}\right)^{13}\)
c) \(4^{50}=\left(4^5\right)^{10}=1024^{10}\)
\(8^{30}=\left(8^3\right)^{10}=512^{10}< 1024^{10}\)
\(\Rightarrow4^{50}>8^{30}\)
d) \(\left(\dfrac{1}{9}\right)^{17}< \left(\dfrac{1}{9}\right)^{12}< \left(\dfrac{1}{27}\right)^{12}\)
\(\Rightarrow\left(\dfrac{1}{9}\right)^{17}< \left(\dfrac{1}{27}\right)^{12}\)
A) -15,5 x 20,8 +2,5 x 9,2 -15,5 x 9,2 + 3,5 x 20,8
=-15,5 x 20,8 + 2,5 x 9,2 + -15,5 x 9,2 +3,5 x 20,8
=[20,8x(-15,5+3,5)]+[9,2x(2,5+-15,5)]
=[20,8x(-12)]+[9,2x(-13)]
=-249,6+-119,6
=-369,2
a) -369,2
b) -7