Question

Simplify the expression and find its value if x is equal to 2.
\[3\left( {x + 2} \right) + 5x - 7\]

Answer 1

Hint: Open the brackets, multiply and gather all the terms having x together and numbers together. Then substitute the value of x = 2 to get the desired answer.

Complete step by step answer:
According to the question, the equation is \[3\left( {x + 2} \right) + 5x - 7\]. This can be further simplified as:
\[ \Rightarrow 3\left( {x + 2} \right) + 5x - 7 = 3x + 6 + 5x - 7\]
Taking all the x terms together and numbers together, we’ll get:
\[
   \Rightarrow 3\left( {x + 2} \right) + 5x - 7 = 3x + 5x + 6 - 7, \\
   \Rightarrow 3\left( {x + 2} \right) + 5x - 7 = 8x - 1 \\
\]
We have to calculate its value for $x = 2$.
So, putting $x = 2$ in the above expression, we’ll get:
$
   \Rightarrow 8 \times 2 - 1 \\
   = 16 - 1 \\
   = 15 \\
$

Therefore, the value of the above expression at x = 2 is 15.

Note: The above expression is a linear expression in one variable. This can be easily simplified. If we come across a more complex polynomial expression which cannot be easily separable, then we can directly put the value of variables to find out the value of the expression.