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60-[15*X+4]=15/2:1/2
60-[15*X+4]=15
15*X+4=60-15
15*X+4=45
15*X=45-4
15*X=41
X=41:15
X=41/15
ko ghi đề
\(60-\left(15.x+4\right)=\frac{15}{2}.\frac{2}{1}\)
\(60-\left(15.x+4\right)=15\)
\(15.x+4=60-15\)
\(15.x+4=45\)
\(15.x=45-4\)
\(15.x=41\)
\(x=41:15\)
\(x=\text{2.7333}\)
a,Ta có: \(\left(x+2\right)^4=\left(x+2\right)^6\)
\(\left(x+2\right)^4-\left(x+2\right)^6=0\)
\(\left(x+2\right)^4\text{[}1-\left(x+2\right)^2\text{]=0}\)
\(\Rightarrow\orbr{\begin{cases}\left(x+2\right)^4=0\\1-\left(x+2\right)^2=0\end{cases}}\)\(\Leftrightarrow\orbr{\begin{cases}x+2=0\\x+2=1\end{cases}}\Leftrightarrow\orbr{\begin{cases}x=-2\\x=-1\end{cases}}\)
Dùng công thức tính tổng
\(1+2+3+...+x=11325\)
\(\Leftrightarrow\frac{x\left(x+1\right)}{2}=11325\)
\(\Leftrightarrow x\left(x+1\right)=22650\)
\(\Leftrightarrow x\left(x+1\right)=150.151\)
Nên x = 150
Vậy ,,,
\(1+2+3+4+...+x=11325\)
\(\Rightarrow\frac{x\left(x+1\right)}{2}=11325\)
\(\Rightarrow x\left(x+1\right)=11325\times2\)
\(\Rightarrow x\left(x+1\right)=22650\)
\(\Rightarrow150\times151=22650\)
\(\Rightarrow x=150\)
\(a,\dfrac{x}{7}=\dfrac{6}{12}\\ x\cdot12=7\cdot6=42\\ x=42:12\\ x=\dfrac{7}{2}\\ b,\dfrac{-5}{x}=\dfrac{20}{28}\\ x\cdot20=\left(-5\right)\cdot28=-140\\ x=\left(-140\right):20\\ x=-7\\ c,\dfrac{x-2}{8}=\dfrac{3}{4}\\ \left(x-2\right)4=8\cdot3=24\\ x-2=24:4\\ x-2=6\\ x=6+2\\ x=8\\ d,\dfrac{x}{-5}=\dfrac{-5}{x}\\ x^2=\left(-5\right)\cdot\left(-5\right)=25\\ x=5\)
(X + 2)4 = (x + 2)6
(x + 2)6 - (x + 2)4 = 0
(x + 2)4.[(x + 2)2 - 1] = 0
\(\Rightarrow\orbr{\begin{cases}\left(x+2\right)^4=0\\\left(x+2\right)^2-1=0\end{cases}}\Rightarrow\orbr{\begin{cases}x+2=0\\\left(x+2\right)^2=1\end{cases}}\Rightarrow\orbr{\begin{cases}x=-2\\\end{cases}}\)
\(\left(x+2\right)^2=1\Rightarrow\orbr{\begin{cases}x+2=-1\\x+2=1\end{cases}}\Rightarrow\orbr{\begin{cases}x=-3\\x=1\end{cases}}\)
=> x = {-3 ; -2 ; 1}