Solve {c}{2(x+n)-y/m=2n}{mx+y-m=0}

$$\left\{ \begin{array} { c } { 2 ( x + n ) - \frac { y } { m } = 2 n } \\ { m x + y - m = 0 } \end{array} \right.$$

Solve for x, y

$$x=\frac{1}{3}\approx 0.333333333$$

$$y=\frac{2m}{3}$$

$$m\neq 0$$

Steps Using Substitution

Consider the first equation. Multiply both sides of the equation by m.

$$2\left(x+n\right)m-y=2nm$$

Use the distributive property to multiply 2 by x+n.

$$\left(2x+2n\right)m-y=2nm$$

Use the distributive property to multiply 2x+2n by m.

$$2xm+2nm-y=2nm$$

Subtract 2nm from both sides.

$$2xm-y=2nm-2nm$$

Combine 2nm and -2nm to get 0.

$$2xm-y=0$$

Consider the second equation. Add m to both sides. Anything plus zero gives itself.

$$mx+y=m$$

To solve a pair of equations using substitution, first solve one of the equations for one of the variables. Then substitute the result for that variable in the other equation.

$$2mx-y=0,mx+y=m$$

Choose one of the equations and solve it for x by isolating x on the left hand side of the equal sign.

$$2mx-y=0$$

Add y to both sides of the equation.

$$2mx=y$$

Divide both sides by 2m.

$$x=\frac{1}{2m}y$$

Substitute \frac{y}{2m} for x in the other equation, mx+y=m.

$$m\times \frac{1}{2m}y+y=m$$

Multiply m times \frac{y}{2m}.

$$\frac{1}{2}y+y=m$$

Add \frac{y}{2} to y.

$$\frac{3}{2}y=m$$

Divide both sides of the equation by \frac{3}{2}, which is the same as multiplying both sides by the reciprocal of the fraction.

$$y=\frac{2m}{3}$$

Substitute \frac{2m}{3} for y in x=\frac{1}{2m}y. Because the resulting equation contains only one variable, you can solve for x directly.

$$x=\frac{1}{2m}\times \frac{2m}{3}$$

Multiply \frac{1}{2m} times \frac{2m}{3}.

$$x=\frac{1}{3}$$

The system is now solved.

$$x=\frac{1}{3},y=\frac{2m}{3}$$

Steps Using Matrices

Consider the first equation. Multiply both sides of the equation by m.

$$2\left(x+n\right)m-y=2nm$$

Use the distributive property to multiply 2 by x+n.

$$\left(2x+2n\right)m-y=2nm$$

Use the distributive property to multiply 2x+2n by m.

$$2xm+2nm-y=2nm$$

Subtract 2nm from both sides.

$$2xm-y=2nm-2nm$$

Combine 2nm and -2nm to get 0.

$$2xm-y=0$$

Consider the second equation. Add m to both sides. Anything plus zero gives itself.

$$mx+y=m$$

Put the equations in standard form and then use matrices to solve the system of equations.

$$2mx-y=0,mx+y=m$$

Write the equations in matrix form.

$$\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right)\left(\begin{matrix}x\\y\end{matrix}\right)=\left(\begin{matrix}0\\m\end{matrix}\right)$$

Left multiply the equation by the inverse matrix of \left(\begin{matrix}2m&-1\\m&1\end{matrix}\right).

$$inverse(\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right))\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right)\left(\begin{matrix}x\\y\end{matrix}\right)=inverse(\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right))\left(\begin{matrix}0\\m\end{matrix}\right)$$

The product of a matrix and its inverse is the identity matrix.

$$\left(\begin{matrix}1&0\\0&1\end{matrix}\right)\left(\begin{matrix}x\\y\end{matrix}\right)=inverse(\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right))\left(\begin{matrix}0\\m\end{matrix}\right)$$

Multiply the matrices on the left hand side of the equal sign.

$$\left(\begin{matrix}x\\y\end{matrix}\right)=inverse(\left(\begin{matrix}2m&-1\\m&1\end{matrix}\right))\left(\begin{matrix}0\\m\end{matrix}\right)$$

For the 2\times 2 matrix \left(\begin{matrix}a&b\\c&d\end{matrix}\right), the inverse matrix is \left(\begin{matrix}\frac{d}{ad-bc}&\frac{-b}{ad-bc}\\\frac{-c}{ad-bc}&\frac{a}{ad-bc}\end{matrix}\right), so the matrix equation can be rewritten as a matrix multiplication problem.

$$\left(\begin{matrix}x\\y\end{matrix}\right)=\left(\begin{matrix}\frac{1}{2m-\left(-m\right)}&-\frac{-1}{2m-\left(-m\right)}\\-\frac{m}{2m-\left(-m\right)}&\frac{2m}{2m-\left(-m\right)}\end{matrix}\right)\left(\begin{matrix}0\\m\end{matrix}\right)$$

Do the arithmetic.

$$\left(\begin{matrix}x\\y\end{matrix}\right)=\left(\begin{matrix}\frac{1}{3m}&\frac{1}{3m}\\-\frac{1}{3}&\frac{2}{3}\end{matrix}\right)\left(\begin{matrix}0\\m\end{matrix}\right)$$

Multiply the matrices.

$$\left(\begin{matrix}x\\y\end{matrix}\right)=\left(\begin{matrix}\frac{1}{3m}m\\\frac{2}{3}m\end{matrix}\right)$$

Do the arithmetic.

$$\left(\begin{matrix}x\\y\end{matrix}\right)=\left(\begin{matrix}\frac{1}{3}\\\frac{2m}{3}\end{matrix}\right)$$

Extract the matrix elements x and y.

$$x=\frac{1}{3},y=\frac{2m}{3}$$

Steps Using Elimination

Consider the first equation. Multiply both sides of the equation by m.

$$2\left(x+n\right)m-y=2nm$$

Use the distributive property to multiply 2 by x+n.

$$\left(2x+2n\right)m-y=2nm$$

Use the distributive property to multiply 2x+2n by m.

$$2xm+2nm-y=2nm$$

Subtract 2nm from both sides.

$$2xm-y=2nm-2nm$$

Combine 2nm and -2nm to get 0.

$$2xm-y=0$$

Consider the second equation. Add m to both sides. Anything plus zero gives itself.

$$mx+y=m$$

In order to solve by elimination, coefficients of one of the variables must be the same in both equations so that the variable will cancel out when one equation is subtracted from the other.

$$2mx-y=0,mx+y=m$$

To make 2mx and mx equal, multiply all terms on each side of the first equation by m and all terms on each side of the second by 2m.

$$m\times 2mx+m\left(-1\right)y=0,2mmx+2my=2mm$$

Simplify.

$$2m^{2}x+\left(-m\right)y=0,2m^{2}x+2my=2m^{2}$$

Subtract 2m^{2}x+2my=2m^{2} from 2m^{2}x+\left(-m\right)y=0 by subtracting like terms on each side of the equal sign.

$$2m^{2}x+\left(-2m^{2}\right)x+\left(-m\right)y+\left(-2m\right)y=-2m^{2}$$

Add 2m^{2}x to -2m^{2}x. Terms 2m^{2}x and -2m^{2}x cancel out, leaving an equation with only one variable that can be solved.

$$\left(-m\right)y+\left(-2m\right)y=-2m^{2}$$

Add -my to -2my.

$$\left(-3m\right)y=-2m^{2}$$

Divide both sides by -3m.

$$y=\frac{2m}{3}$$

Substitute \frac{2m}{3} for y in mx+y=m. Because the resulting equation contains only one variable, you can solve for x directly.

$$mx+\frac{2m}{3}=m$$

Subtract \frac{2m}{3} from both sides of the equation.

$$mx=\frac{m}{3}$$

Divide both sides by m.

$$x=\frac{1}{3}$$

The system is now solved.

$$x=\frac{1}{3},y=\frac{2m}{3}$$