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\(M=\frac{2.2^{12}.3^6+2^2.2^9.3^9}{2^5.2^7.3^7+2^7.2^3.3^{10}}\)
\(=\frac{2^{11}.3^6\left(2^2+3^3\right)}{2^{10}.3^7\left(2^2+3^3\right)}\)
\(=\frac{2}{3}\)
\(M=\frac{2.\left(2^3\right)^4.\left(3^3\right)^2+2^2.\left(2.3\right)^9}{2^5.\left(2.3\right)^7+2^7.2^3.\left(3^2\right)^5}\)
\(M=\frac{2.2^{12}.3^6+2^2.2^9.3^9}{2^5.2^7.3^7+2^7.2^3.3^{10}}\)
\(M=\frac{2^{13}.3^6+2^{11}.3^9}{2^{12}.3^7+2^{10}.3^{10}}\)
\(M=\frac{2^{11}.3^6\left(2^2.1+1.3^3\right)}{2^{10}.3^7\left(2^2.1+1.3^3\right)}\)
\(M=\frac{2.31}{3.31}\)
\(M=\frac{2}{3}\)
Study well
\(6^x+4\cdot6^x=180\)
\(6^x\cdot\left(1+4\right)=36\cdot5\)
\(6^x\cdot5=36\cdot5\)
\(6^x=36\)
\(6^x=6^2\)
\(x=2\)
Áp dụng định lí tổng ba góc trong tam giác, ta có:
+)
\(\begin{array}{l}x + {120^o} + {35^o} = {180^o}\\ \Rightarrow x + {155^o} = {180^o}\\ \Rightarrow x = {180^o} - {155^o}\\ \Rightarrow x = {25^o}\end{array}\)
+)
\(\begin{array}{l}y + {70^o} + {60^o} = {180^o}\\ \Rightarrow y = {180^o} - {70^o} - {60^o}\\ \Rightarrow y = {50^o}\end{array}\)
+)
\(\begin{array}{l}z+ {90^o} + {55^o} = {180^o}\\ \Rightarrow z = {180^o} - {90^o} - {55^o}\\ \Rightarrow z = {35^o}\end{array}\)
x=180-120-35=180-155=25 độ
y=180-70-60=50 độ
z=180-90-55=35 độ
Gọi biểu thức trên là A
Ta có:
2A = (\(\dfrac{1}{2.4}\)+\(\dfrac{1}{4.6}\)+...+\(\dfrac{1}{x.\left(x+2\right)}\)).2
2A = \(\dfrac{2}{2.4}\)+\(\dfrac{2}{4.6}\)+...+\(\dfrac{2}{x\left(x+2\right)}\)
2A = \(\dfrac{1}{2}\)-\(\dfrac{1}{4}\)+\(\dfrac{1}{4}\)-\(\dfrac{1}{6}\)+...+\(\dfrac{1}{x}\)-\(\dfrac{1}{x+2}\)
2A = \(\dfrac{1}{2}\)-\(\dfrac{1}{x+2}\)
mà A = \(\dfrac{1}{10}\)(đề bài)
nên 2A = \(\dfrac{2}{10}\) hay \(\dfrac{1}{2}\) - \(\dfrac{1}{x+2}\) = \(\dfrac{2}{10}\)
suy ra \(\dfrac{1}{x+2}\) = \(\dfrac{1}{2}\)-\(\dfrac{2}{10}\)=\(\dfrac{3}{10}\)
\(\frac{1}{3.4}+\frac{1}{3.4}+...+\frac{1}{x\left(x+1\right)}=\frac{1}{3}-\frac{1}{x+1}\)
\(\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{x\left(x+1\right)}\)
\(=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+.....+\frac{1}{x}-\frac{1}{x+1}\)
\(=\frac{1}{3}-\frac{1}{x+1}\)
|5.6 - \(x\)| = 4.6
|30 - \(x\)| = 24
\(x< 30\) ⇒ 30 - \(x\) = 24 ⇒ \(x\) = 30 - 24 = -6
\(x>30\) ⇒ -(30 - \(x\)) = 24 ⇒ -30 + \(x\) = 24 ⇒ \(x\) = 24 + 30 = 54
Vậy \(x\) \(\in\) { -6; 54}
`@` `\text {Ans}`
`\downarrow`
\(\left|5\cdot6-x\right|=4\cdot6\)
`\Rightarrow`\(\left|5\cdot6-x\right|=24\)
`\Rightarrow`\(\left[{}\begin{matrix}5\cdot6-x=24\\5\cdot6-x=-24\end{matrix}\right.\)
`\Rightarrow`\(\left[{}\begin{matrix}30-x=24\\30-x=-24\end{matrix}\right.\)
`\Rightarrow`\(\left[{}\begin{matrix}x=30-24\\x=30-\left(-24\right)\end{matrix}\right.\)
`\Rightarrow`\(\left[{}\begin{matrix}x=6\\x=54\end{matrix}\right.\)
Vậy, `x={6; 54}.`