Solve {l}{3x+y=7}{9x+1=x}

$$\left\{ \begin{array} { l } { 3 x + y = 7 } \\ { 9 x + 1 = x } \end{array} \right.$$

Solve for x, y

$$x=-\frac{1}{8}=-0.125$$

$$y = \frac{59}{8} = 7\frac{3}{8} = 7.375$$

Solution Steps

Consider the second equation. Subtract x from both sides.

$$9x+1-x=0$$

Combine 9x and -x to get 8x.

$$8x+1=0$$

Subtract 1 from both sides. Anything subtracted from zero gives its negation.

$$8x=-1$$

Divide both sides by 8.

$$x=-\frac{1}{8}$$

Consider the first equation. Insert the known values of variables into the equation.

$$3\left(-\frac{1}{8}\right)+y=7$$

Multiply 3 and -\frac{1}{8} to get -\frac{3}{8}.

$$-\frac{3}{8}+y=7$$

Add \frac{3}{8} to both sides.

$$y=7+\frac{3}{8}$$

Add 7 and \frac{3}{8} to get \frac{59}{8}.

$$y=\frac{59}{8}$$

The system is now solved.

$$x=-\frac{1}{8} y=\frac{59}{8}$$