Tìm y:
Y÷4×Y+0,25=2,45
Y×2+Y×0,5=6,25
99,75÷(Y×6)=4,75
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Ta có:
\(\left(x-0,5\right)^2+\left(y+0,25\right)^2=0\)
\(\Leftrightarrow x-0,5=y+0,25=0\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=0,5\\y=-0,25\end{matrix}\right.\)
\(y+y:0,5+y:0,25+y:0,125=15\)
\(y.1+y.2+y.4+y.8=15\)
\(y.\left(1+2+4+8\right)=15\)
\(y.15=15\)
\(y=1\)
. là dấu nhân!
\(\left(x-0,5\right)^2+\left(y+0,25\right)^2=0\)
Do \(\hept{\begin{cases}\left(x-0,5\right)^2\ge0\\\left(y+0,25\right)^2\ge0\end{cases}\Rightarrow VT\ge0}\)
Dấu "=" xảy ra \(\Leftrightarrow\hept{\begin{cases}x-0,5=0\\y+0,25=0\end{cases}\Leftrightarrow\hept{\begin{cases}x=0,5\\y=-0,25\end{cases}}}\)
Vậy \(\hept{\begin{cases}x=0,5\\y=-0,25\end{cases}}\)
vì \(\hept{\begin{cases}\left(x-0,5\right)^2\ge0\\\left(y+0,25\right)\ge0\end{cases}}\)
mà \(\left(x-0,25\right)^2+\left(y-0,25\right)^2=0\)
\(\Rightarrow\hept{\begin{cases}\left(x+0,5\right)^2=0\\\left(y-0,25\right)^2=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x+0,5=0\\y-0,25=0\end{cases}}\)
\(\Rightarrow\hept{\begin{cases}x=-0,5\\y=0,25\end{cases}}\)
1)\(y\times7:5+4\times8=134\)
\(\Leftrightarrow y\times7:5+32=134\)
\(\Leftrightarrow y\times7:5=102\)
\(\Leftrightarrow y\times7=510\)
\(\Leftrightarrow y=72,86\)
2) \(\dfrac{1}{4}:0,25-\dfrac{1}{8}:0,125+\dfrac{1}{2}:0,5-\dfrac{1}{10}\)
\(=0,25:0,25-0,125:0,125+0,5:0,5-\dfrac{1}{10}\)
\(=1-1+1-\dfrac{1}{10}\)
\(=\dfrac{9}{10}\)
2/ Tìm y:
y + \(\dfrac{1}{3}\) x 4 = 12 \(\dfrac{2}{5}\) + y = \(\dfrac{12}{35}\) x \(\dfrac{14}{9}\)
\(y=12-\left(\dfrac{1}{3}\times4\right)=12-\dfrac{4}{3}=\dfrac{32}{3}\)
\(y=\left(\dfrac{12}{35}\times\dfrac{14}{9}\right)-\dfrac{2}{5}=\dfrac{8}{15}-\dfrac{2}{5}=\dfrac{2}{15}\)
Câu 1 ko hiểu đề bài lắm
\(2.Y\times\left(2+0,5\right)=6,25\)
\(Y\times2,5=6,25\)
\(Y=6,25:2,5\)
\(Y=2,5\)
\(3.Y\times6=99,75:4,75\)
\(Y\times6=21\)
\(Y=21:6\)
\(Y=3,5\)