Solve {l}{7x+9x(-6-2x)=m}{3x-(-6-2x)+29=0}

$$\left. \begin{array} { l } { 7 x + 9 x ( - 6 - 2 x ) = m } \\ { 3 x - ( - 6 - 2 x ) + 29 = 0 } \end{array} \right.$$

Solve for x, m

$$x=-7$$

$$m=-553$$

Solution Steps

Consider the second equation. To find the opposite of -6-2x, find the opposite of each term.

$$3x+6+2x+29=0$$

Combine 3x and 2x to get 5x.

$$5x+6+29=0$$

Add 6 and 29 to get 35.

$$5x+35=0$$

Subtract 35 from both sides. Anything subtracted from zero gives its negation.

$$5x=-35$$

Divide both sides by 5.

$$x=\frac{-35}{5}$$

Divide -35 by 5 to get -7.

$$x=-7$$

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

$$7\left(-7\right)+9\left(-7\right)\left(-6-2\left(-7\right)\right)=m$$

Do the multiplications.

$$-49-63\left(-6-2\left(-7\right)\right)=m$$

Multiply -2 and -7 to get 14.

$$-49-63\left(-6+14\right)=m$$

Add -6 and 14 to get 8.

$$-49-63\times 8=m$$

Multiply -63 and 8 to get -504.

$$-49-504=m$$

Subtract 504 from -49 to get -553.

$$-553=m$$

Swap sides so that all variable terms are on the left hand side.

$$m=-553$$

The system is now solved.

$$x=-7 m=-553$$