9.5 x X + 2.5 x ( 1 - X ) = 3.95 hỏi X =
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\(2,5\) x \(9,5\) x \(4+20\) x \(9,5\) x \(0,5\) +\(9,5\) x \(8\) x \(1,25\)
\(=9,5\) x ( \(2,5\) x \(4+20\) x \(0,5\) + \(8\) x \(1,25\) )
\(=9,5\) x \(30\)
\(=285\)
`2,5xx9,5xx4+20xx9,5xx0,5+9,5xx8xx1,25`
`=9,5xx10+9,5xx10+9,5xx10`
`=9,5xx(10+10+10)`
`=9,5xx30`
`=285`
3,95 x 1/4 + 3,95 x 9,85 - 3,95 : 10
= 3,95 x 0,25 + 3,95 x 9,85 - 3,95 x 0,1
= 3,95 x ( 0,25 + 9,85 - 0,1 )
= 3,95 x 10
= 39,5
\(9,5\times3,7+9,5\times1,3+9,5:0,25+9,5\)
\(=9,5\times3,7+9,5\times1,3+9,5\times4+9,5\)
\(=9,5\times\left(3,7+1,3+4+1\right)\)
\(=9,5\times10\)
\(=95\)
Câu 2:
\(B=\dfrac{5^{21}\cdot\left(2\cdot5-9\right)}{5^{20}}\cdot\dfrac{7^{15}\left(7+3\right)}{15\cdot7^{15}-95\cdot7^{14}}\)
\(=\dfrac{5\cdot1}{1}\cdot\dfrac{7^{15}\cdot10}{7^{14}\cdot\left(15\cdot7-95\right)}\)
\(=5\cdot\dfrac{7\cdot10}{105-95}=5\cdot7=35\)
\(9,5x+2,5\left(1-x\right)=3,95\)
\(\Leftrightarrow9,5x+2,5-2,5x=3,95\)
\(\Leftrightarrow7x=1,45\)
\(\Leftrightarrow x=\dfrac{29}{140}\)
9,5.x+2,5.(1-x)=3,95`
`⇒` `(14x+5)/2` `=` `79/20`
`⇒` `((14x+5).20)/20` `=` `(2.79)/20`
`⇒` `(4x+5).20=2.79`
`⇒` `14x+5=79/10`
`⇒` `14x=29/10`
`⇒` `x` `=` `29/140` `≈` `0,2071`