[x - 2 ] . [ x - 2 ] = 36 - 4 . 5 {ko làm theo cách lũy thừa }
Dấu chấm là nhân nha
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\(x^4\cdot x^7\cdot...\cdot x^{100}\)
\(=x^{4+7+...+100}\)
\(=x^{52\cdot33}=x^{1716}\)
\(x^1\cdot x^2\cdot x^3\cdot...\cdot x^{2006}\)
Ta có : \(x^1\cdot x^2=x^{1+2}=x^3\)
Tương tự : \(x^1\cdot x^2\cdot x^3=x^{1+2+3}=x^6\)
Áp dụng vào bài toán :
\(x^1\cdot x^2\cdot x^3\cdot...\cdot x^{2006}=x^{1+2+3+...+2006}\)
\(\Rightarrow x^{1+2+3+...+2006}=x^{2013021}\)
\(1,\\ a,\Rightarrow x=\dfrac{5\cdot4}{3}=\dfrac{20}{3}\\ b,\Rightarrow x=8\\ c,\Rightarrow x=\dfrac{27\cdot2}{3,6}=15\\ 2,\\ a,\dfrac{6}{9}=\dfrac{42}{63};\dfrac{6}{42}=\dfrac{9}{63};\dfrac{63}{9}=\dfrac{42}{6};\dfrac{63}{42}=\dfrac{9}{6}\\ b,\dfrac{4}{18}=\dfrac{2}{9};\dfrac{4}{2}=\dfrac{18}{9};\dfrac{9}{18}=\dfrac{2}{4};\dfrac{9}{2}=\dfrac{18}{4}\)
a) \(215+x=400\)
\(\Rightarrow x=400-215\)
\(\Rightarrow x=185\)
b) \(12,5-2x=\dfrac{1}{5}\)
\(\Rightarrow2x=12,5-\dfrac{1}{5}\)
\(\Rightarrow2x=\dfrac{123}{10}\)
\(\Rightarrow x=\dfrac{123}{10}:2\)
\(\Rightarrow x=\dfrac{123}{20}\)
3.x + 2.x + x = 300
x.(3+2+1) = 300
x.6 = 300
x=300 : 6
x = 50
\(4\left(x+2\right)-8\left(x+3\right)=36\)
\(\Rightarrow4x+8-8x-24=36\)
\(\Rightarrow4x-8x=36+24-8\)
\(\Rightarrow-4x=52\)
\(\Rightarrow x=-13\)
a) \(\frac{1}{3}+\frac{5}{6}:\left(x-2\frac{1}{5}\right)=\frac{3}{4}\)
=> \(\frac{1}{3}+\frac{5}{6}:\left(x-\frac{11}{5}\right)=\frac{3}{4}\)
=> \(\frac{5}{6}:\left(x-\frac{11}{5}\right)=\frac{3}{4}-\frac{1}{3}\)
=> \(\frac{5}{6}:\left(x-\frac{11}{5}\right)=\frac{5}{12}\)
=> \(x-\frac{11}{5}=\frac{5}{6}:\frac{5}{12}\)
=> \(x-\frac{11}{5}=2\)
=> \(x=2+\frac{11}{5}\)
=> \(x=\frac{21}{5}\)
a) \(\left(x^2-9\right)\cdot\left(4^x-16\right)=0\)
\(\Rightarrow x^2-9=0\)hoặc \(4^x-16=0\)
\(x^2=9\) \(4^x=16\)
\(x^2=\left(\pm3\right)^2\) \(4^x=4^2\)
\(\Rightarrow x=\pm3\)hoặc \(x=2\)
b) \(5^x+5^{x+2}=650\)
\(\Rightarrow5^x+5^x\cdot25=650\)
\(\Rightarrow5^x\cdot\left(1+25\right)=650\)
\(\Rightarrow5^x\cdot26=650\)
\(\Rightarrow5^x=650\div26=25\)
\(\Rightarrow5^x=5^2\)
\(\Rightarrow x=2\)Vậy \(x=2\)
c) \(2^{x+2}-2^x=96\)
\(2^x\cdot4-2^x=96\)
\(2^x\cdot\left(4-1\right)=96\)
\(2^x\cdot3=96\)
\(2^x=96\div3=32\)
\(2^x=2^5\)Vậy \(x=5\)
.......................................[đề bài]
[X-2]x[X-2]=36-20=16
=>mỗi ngoặc phải bằng 4 vì 4x4=16
X-2=4
X=4+2
X=6