Tìm x
x - 25%x - 1/2.x = -5/4
mik đang cần gấp ah
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a) \(\left(\frac{2x}{5}-1\right):\left(-5\right)=\frac{1}{7}\)
\(\frac{2x}{5}-1=\frac{1}{7}.\left(-5\right)\)
\(\frac{2x}{5}-1=\frac{-5}{7}\)
\(\frac{2x}{5}=\frac{-5}{7}+\frac{7}{7}\)
\(\frac{2x}{5}=\frac{2}{7}\)
\(=>2x.7=2.5\)
\(=>14x=10\)
\(=>x=\frac{5}{7}\)
c) \(\left|3,5+2,5x\right|-2,5=3,5\)
\(\left|3,5+2,5x\right|=3,5+2,5\)
\(\left|3,5+2,5x\right|=6\)
\(TH1\) \(3,5+2,5x=6\) \(TH2\) \(3,5+2,5x=-6\)
\(2,5x=6-3,5\) \(2,5x=-6-3,5\)
\(2,5x=2,5\) \(2,5x=-9.5\)
\(x=1\) \(x=-3,8\)
vậy \(x=1\) hoặc \(x=-3,8\)
câu d) làm tương tự như câu c)
`x/2+x+x/3+x+x+x/4=5 3/4`
`=>3x+x/2+x/3+x/4=23/4`
`=>49/12x=23/4`
`=>x=69/49`
Vậy `x=69/49`
Ta có :
\(\frac{x-1}{27}+\frac{x-2}{26}+\frac{x-3}{25}+\frac{x-4}{24}=4\)
\(\Leftrightarrow\)\(\left(\frac{x-1}{27}-1\right)+\left(\frac{x-2}{26}-1\right)+\left(\frac{x-3}{25}-1\right)+\left(\frac{x-4}{24}-1\right)=4-4\) ( trừ 2 vế cho 4 )
\(\Leftrightarrow\)\(\frac{x-28}{27}+\frac{x-28}{26}+\frac{x-28}{25}+\frac{x-28}{24}=0\)
\(\Leftrightarrow\)\(\left(x-28\right)\left(\frac{1}{27}+\frac{1}{26}+\frac{1}{25}+\frac{1}{24}\right)=0\)
Vì \(\frac{1}{27}+\frac{1}{26}+\frac{1}{25}+\frac{1}{24}\ne0\)
Nên \(x-28=0\)
\(\Rightarrow\)\(x=28\)
Vậy \(x=28\)
Chúc bạn học tốt ~
\(x-\frac{1}{27}+x-\frac{2}{26}+x-\frac{3}{25}+x-\frac{4}{24}=4\)
\(\left(x+x+x+x\right)-\left(\frac{1}{27}+\frac{2}{26}+\frac{3}{25}+\frac{4}{24}\right)=4\)
\(4x-\frac{7031}{17550}=4\)
\(4x=4+\frac{7031}{17550}\)
\(x=\frac{4+\frac{7031}{17550}}{4}=1+\frac{\frac{7031}{17550}}{4}\)
\(x=1+\frac{7031}{70200}\)
.........................................................................................
\(a,\Leftrightarrow\left(5x+1\right)\left(x-4\right)-\left(x-4\right)=0\\ \Leftrightarrow\left(x-4\right)\left(5x+1-x\right)=0\\ \Leftrightarrow5x\left(x-4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=0\\x=4\end{matrix}\right.\\ b,\Leftrightarrow2x^2-10x-2x^2-3x=26\\ \Leftrightarrow-13x=26\\ \Leftrightarrow x=-2\\ c,\Leftrightarrow x^3+1-x^3+3x=15\\ \Leftrightarrow3x=14\\ \Leftrightarrow x=\dfrac{14}{3}\)
\(d,\Leftrightarrow x^3-5x+2x^2-10+5x-2x^2-17=0\\ \Leftrightarrow x^3-27=0\\ \Leftrightarrow x^3=27\\ \Leftrightarrow x=3\)
\(4^{x+3}+4^{x+2}+4^{x+1}+4^x=5440\)
\(\Rightarrow4^x.4^3+4^x.4^2+4^x.4+4^x=5440\)
\(\Rightarrow4^x\left(4^3+4^2+4+1\right)=5440\)
\(\Rightarrow4^x.\left(64+16+4+1\right)=5440\)
\(\Rightarrow4^x.85=5440\)
\(\Rightarrow4^x=5440:85\)
\(\Rightarrow4^x=64=4^3\)
\(\Rightarrow x=3\)
dễ quá bạn ơi giải câu này nè mới chất
Q= 12 + 22 + 32 +...+ 1002
Bài 1 d)
\(1-2+3-4+5-6+...+2013\)
\(=1+\left(-2+3\right)+\left(-4+5\right)+...+\left(-2012+2013\right)\)
\(=1+1+1+...+1\left(1006s\right)\)
\(=1006.1=1006\)
Lời giải:
$x-25\text{%}x-\frac{1}{2}=\frac{-5}{4}$
$x-0,25x=\frac{1}{2}-\frac{5}{4}$
$x(1-0,25)=\frac{-3}{4}$
$x.0,75=\frac{-3}{4}$
$x=\frac{-3}{4}: 0,75=\frac{-3}{4}: \frac{3}{4}=-1$
x - 25% .x - 1/2 = -5/4
x - 1/4 . x - 1/2 = -5/4
(x.x ) - (1/4 - 1/2) = -5/4
2x - -1/4 = -5/4
2x + 1/4 = -5/4
2x = -5/4 - 1/4
2x = -3/2
x = -3/2 : 2 ( -3/2 x 1/2)
x = -3/4