Solve for k
k=-\frac{5\left(x-4\right)}{x^{2}}
x\neq 0
Solve for x (complex solution)
\left\{\begin{matrix}x=\frac{\sqrt{5\left(16k+5\right)}-5}{2k}\text{; }x=-\frac{\sqrt{5}\left(\sqrt{16k+5}+\sqrt{5}\right)}{2k}\text{, }&k\neq 0\\x=4\text{, }&k=0\end{matrix}\right.
Solve for x
\left\{\begin{matrix}x=\frac{\sqrt{5\left(16k+5\right)}-5}{2k}\text{; }x=-\frac{\sqrt{5}\left(\sqrt{16k+5}+\sqrt{5}\right)}{2k}\text{, }&k\neq 0\text{ and }k\geq -\frac{5}{16}\\x=4\text{, }&k=0\end{matrix}\right.
Graph
Share
Copied to clipboard
kx^{2}+5x=5\times 4
Multiply both sides by 4.
kx^{2}+5x=20
Multiply 5 and 4 to get 20.
kx^{2}=20-5x
Subtract 5x from both sides.
x^{2}k=20-5x
The equation is in standard form.
\frac{x^{2}k}{x^{2}}=\frac{20-5x}{x^{2}}
Divide both sides by x^{2}.
k=\frac{20-5x}{x^{2}}
Dividing by x^{2} undoes the multiplication by x^{2}.
k=\frac{5\left(4-x\right)}{x^{2}}
Divide 20-5x by x^{2}.
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}