Solve for f
f=\frac{4x}{x+1}
x\neq 0\text{ and }x\neq -1
Solve for x
x=\frac{f}{4-f}
f\neq 4\text{ and }f\neq 0
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4f^{-1}x=x+1
Multiply both sides of the equation by 4.
4\times \frac{1}{f}x=x+1
Reorder the terms.
4\times 1x=fx+f
Variable f cannot be equal to 0 since division by zero is not defined. Multiply both sides of the equation by f.
4x=fx+f
Multiply 4 and 1 to get 4.
fx+f=4x
Swap sides so that all variable terms are on the left hand side.
\left(x+1\right)f=4x
Combine all terms containing f.
\frac{\left(x+1\right)f}{x+1}=\frac{4x}{x+1}
Divide both sides by x+1.
f=\frac{4x}{x+1}
Dividing by x+1 undoes the multiplication by x+1.
f=\frac{4x}{x+1}\text{, }f\neq 0
Variable f cannot be equal to 0.
4f^{-1}x=x+1
Multiply both sides of the equation by 4.
4f^{-1}x-x=1
Subtract x from both sides.
-x+4\times \frac{1}{f}x=1
Reorder the terms.
-xf+4\times 1x=f
Multiply both sides of the equation by f.
-xf+4x=f
Multiply 4 and 1 to get 4.
\left(-f+4\right)x=f
Combine all terms containing x.
\left(4-f\right)x=f
The equation is in standard form.
\frac{\left(4-f\right)x}{4-f}=\frac{f}{4-f}
Divide both sides by 4-f.
x=\frac{f}{4-f}
Dividing by 4-f undoes the multiplication by 4-f.
Examples
Quadratic equation
{ x } ^ { 2 } - 4 x - 5 = 0
Trigonometry
4 \sin \theta \cos \theta = 2 \sin \theta
Linear equation
y = 3x + 4
Arithmetic
699 * 533
Matrix
\left[ \begin{array} { l l } { 2 } & { 3 } \\ { 5 } & { 4 } \end{array} \right] \left[ \begin{array} { l l l } { 2 } & { 0 } & { 3 } \\ { -1 } & { 1 } & { 5 } \end{array} \right]
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
\lim _{x \rightarrow-3} \frac{x^{2}-9}{x^{2}+2 x-3}