Question

Subtract 3x − 4y − 7z from the sum of x − 3y + 2z and − 4x + 9y − 11z.

Answer 1

Let first add the expressions 

\[x - 3y + 2z \text { and } - 4x + 9y - 11z\] We get:

\[\left( x - 3y + 2z \right) + \left( - 4x + 9y - 11z \right)\]

\[= x - 3y + 2z - 4x + 9y - 11z\]

\[= x - 4x - 3y + 9y + 2z - 11z\]                  (Collecting like terms)          

\[= - 3x + 6y - 9z\]                         (Combining like terms)

Now, subtracting the expression

\[3x - 4y - 7z\]  from the above sum; we get:

\[\left( - 3x + 6y - 9z \right) - \left( 3x - 4y - 7z \right)\]

\[ = - 3x + 6y - 9z - 3x + 4y + 7z\]

\[= - 3x - 3x + 6y + 4y - 9z + 7z\]         (Collecting like terms)

\[= - 6x + 10y - 2z\]                   (Combining like terms)

Thus, the answer is \[- 6x + 10y - 2z\].