Solve for x
x=\frac{y-21}{9}
Solve for y
y=9x+21
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y-3-9=9\left(x+1\right)
Multiply both sides of the equation by 3.
y-12=9\left(x+1\right)
Subtract 9 from -3 to get -12.
y-12=9x+9
Use the distributive property to multiply 9 by x+1.
9x+9=y-12
Swap sides so that all variable terms are on the left hand side.
9x=y-12-9
Subtract 9 from both sides.
9x=y-21
Subtract 9 from -12 to get -21.
\frac{9x}{9}=\frac{y-21}{9}
Divide both sides by 9.
x=\frac{y-21}{9}
Dividing by 9 undoes the multiplication by 9.
x=\frac{y}{9}-\frac{7}{3}
Divide y-21 by 9.
y-3-9=9\left(x+1\right)
Multiply both sides of the equation by 3.
y-12=9\left(x+1\right)
Subtract 9 from -3 to get -12.
y-12=9x+9
Use the distributive property to multiply 9 by x+1.
y=9x+9+12
Add 12 to both sides.
y=9x+21
Add 9 and 12 to get 21.
Examples
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y = 3x + 4
Arithmetic
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Matrix
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Simultaneous equation
\left. \begin{cases} { 8x+2y = 46 } \\ { 7x+3y = 47 } \end{cases} \right.
Differentiation
\frac { d } { d x } \frac { ( 3 x ^ { 2 } - 2 ) } { ( x - 5 ) }
Integration
\int _ { 0 } ^ { 1 } x e ^ { - x ^ { 2 } } d x
Limits
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