1)Tìm y biết
a)18 + 2 x y = 50
b)219 - (y - 19) = 100
c)2 x (y - 12) + 18 = 164
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\(a,127-\left(y-15\right)=86\)
\(y-15=127-86\)
\(y-15=41\)
\(y=41+15\)
\(y=56\)
\(b,2\times\left(y-12\right)+18=164\)
\(2\times\left(y-12\right)=164-18\)
\(2\times\left(y-12\right)=146\)
\(y-12=146:2\)
\(y-12=73\)
\(y=73+12\)
\(y=85\)
Học tốt
a)
y + 2,3 = 15,7 - 2,4
y + 2,3 = 13,3
y = 13,3 - 2,3
y = 11
Vậy y = 11
b)
127 - (y - 15) = 86
y - 15 = 127 - 86
y - 15 = 41
y = 41 + 15
y = 56
Vậy y = 56
c)
2 x (y - 12) + 18 = 164
2 x ( y - 12 ) = 164 - 18
2 x ( y - 12 ) = 146
y - 12 = 146 : 2
y - 12 = 73
y = 73 + 12
y = 85
Vậy y = 85
a) y + 2,3 = 15,7 - 2,4
y+2,3=13,3
y=11
b) 127 - (y - 15) = 86
y-15=41
y=56
c) 2 .(y - 12) + 18 = 164
2 .(y - 12) =146
y-12=73
y=85
a) y+2,3=15,724
=>y =15,724 - 2,3
=>y = 13,424
b) 127-(y-15)=86
=> y-15 = 127-86
=> y-15 = 41
=> y = 41+15
=> y = 56
c) 2 x (y-12)+18 = 164
=> 2 x (y-12) = 146
=> y-12 = 73
=> y = 73 + 12
=> y = 85
a) \(y+2,3=15,724\)
\(y=15,724-2,3\)
\(y=13,424\)
b) \(127-\left(y-15\right)=86\)
\(y-15=127-86\)
\(y-15=41\)
\(y=41+15\)
\(y=56\)
c) \(2\cdot\left(x-12\right)+18=164\)
\(2\cdot\left(x-12\right)=164-18\)
\(2\cdot\left(x-12\right)=146\)
\(x-12=146:2\)
\(x-12=73\)
\(x=73+12\)
\(x=85\)
a; 100% : \(x\) - 50% : \(x\) + 40% : \(x\) = 18 + 30% : \(x\)
(100% - 50% + 40%): \(x\) = 18 + 30% : \(x\)
90% : \(x\) = 18 + 30% : \(x\)
90%: \(x\) - 30%: \(x\) = 18
60% : \(x\) = 18
\(x\) = 60% : 18
\(x\) = \(\dfrac{1}{30}\)
a: =>-12<x<2y<-9
=>x=-11; y=-5
b: =>-7<3(x-1)<8
\(\Leftrightarrow3\left(x-1\right)\in\left\{-6;-3;0;3;6\right\}\)
\(\Leftrightarrow x-1\in\left\{2;1;0;-1;-2\right\}\)
hay \(x\in\left\{3;2;1;0;-1\right\}\)
\(a,\dfrac{x}{5}=\dfrac{-18}{10}\\ \Rightarrow x=-\dfrac{18}{10}.5\\ \Rightarrow x=-9\\ b,\dfrac{6}{x-1}=\dfrac{-3}{7}\\ \Rightarrow6.7=-3\left(x-1\right)\\ \Rightarrow42=-3x+3\\ \Rightarrow42+3x-3=0\\ \Rightarrow3x+39=0\\ \Rightarrow3x=-39\\ \Rightarrow x=-13\\ c,\dfrac{y-3}{12}=\dfrac{3}{y-3}\\ \Rightarrow\left(y-3\right)^2=36\\ \Rightarrow\left[{}\begin{matrix}y-2=6\\y-2=-6\end{matrix}\right.\\ \Rightarrow\left[{}\begin{matrix}y=8\\y=-4\end{matrix}\right.\)
\(d,\dfrac{x}{25}=\dfrac{-5}{x^2}\\ \Rightarrow x^3=-125\\ \Rightarrow x^3=\left(-5\right)^3\\ \Rightarrow x=-5\)
a)18 + 2 x y = 50
2 x y = 50 - 18
2 x y = 32
y = 32 : 2
y = 16
b)219 - (y - 19) = 100
(y - 19) = 219 - 100
(y - 19) = 119
y = 119 - 19
y = 100
c)2 x (y - 12) + 18 = 164
2 x (y - 12) = 164 - 18
2 x (y - 12) = 146
( y - 12 ) = 146 : 2
( y - 12 ) = 73
y = 73 - 12
y = 61