Question

$$\frac{ 1 }{ x } + \frac{ 4 }{ y } =1,x=5,y=0$$

Answer

$$x=y/(y-4),(2-sqrt(4+y^2))/y,(2+sqrt(4+y^2))/y$$

Solution


Rewrite the expression with a common denominator.
\[\begin{aligned}&\frac{y+4x}{xy}=1\\&x=5\\&y=0\end{aligned}\]
Break down the problem into these 2 equations.
\[\frac{y+4x}{xy}=1\]
\[\frac{y+4x}{xy}=x\]
Solve the 1st equation: \(\frac{y+4x}{xy}=1\).
\[x=\frac{y}{y-4}\]
Solve the 2nd equation: \(\frac{y+4x}{xy}=x\).
\[x=\frac{2-\sqrt{4+{y}^{2}}}{y},\frac{2+\sqrt{4+{y}^{2}}}{y}\]
Collect all solutions.
\[x=\frac{y}{y-4},\frac{2-\sqrt{4+{y}^{2}}}{y},\frac{2+\sqrt{4+{y}^{2}}}{y}\]