Solve for k
k = -\frac{40}{7} = -5\frac{5}{7} \approx -5.714285714
Share
Copied to clipboard
-\frac{7}{8}k-\frac{2}{7}-\frac{2}{5}k=7
Subtract \frac{2}{5}k from both sides.
-\frac{51}{40}k-\frac{2}{7}=7
Combine -\frac{7}{8}k and -\frac{2}{5}k to get -\frac{51}{40}k.
-\frac{51}{40}k=7+\frac{2}{7}
Add \frac{2}{7} to both sides.
-\frac{51}{40}k=\frac{49}{7}+\frac{2}{7}
Convert 7 to fraction \frac{49}{7}.
-\frac{51}{40}k=\frac{49+2}{7}
Since \frac{49}{7} and \frac{2}{7} have the same denominator, add them by adding their numerators.
-\frac{51}{40}k=\frac{51}{7}
Add 49 and 2 to get 51.
k=\frac{51}{7}\left(-\frac{40}{51}\right)
Multiply both sides by -\frac{40}{51}, the reciprocal of -\frac{51}{40}.
k=\frac{51\left(-40\right)}{7\times 51}
Multiply \frac{51}{7} times -\frac{40}{51} by multiplying numerator times numerator and denominator times denominator.
k=\frac{-40}{7}
Cancel out 51 in both numerator and denominator.
k=-\frac{40}{7}
Fraction \frac{-40}{7} can be rewritten as -\frac{40}{7} by extracting the negative sign.
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}