Solve for x
x=\frac{y-9}{4}
Solve for y
y=4x+9
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-4x=9-y
Subtract y from both sides.
\frac{-4x}{-4}=\frac{9-y}{-4}
Divide both sides by -4.
x=\frac{9-y}{-4}
Dividing by -4 undoes the multiplication by -4.
x=\frac{y-9}{4}
Divide 9-y by -4.
y=9+4x
Add 4x to both sides.
Examples
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{ x } ^ { 2 } - 4 x - 5 = 0
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Linear equation
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Arithmetic
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Matrix
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Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
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\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
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Limits
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