SOLUTION: I have a question that states: evaluate the function at the specified value(s) of the independent variable and simplify. f(x)=/x/+7; f(-9). I thought this was -2 but I guess I a

Algebra ->  Graphs -> SOLUTION: I have a question that states: evaluate the function at the specified value(s) of the independent variable and simplify. f(x)=/x/+7; f(-9). I thought this was -2 but I guess I a      Log On


   



Question 84962: I have a question that states: evaluate the function at the specified value(s) of the independent variable and simplify. f(x)=/x/+7; f(-9). I thought this was -2 but I guess I am wrong.
Answer by bucky(2189) About Me  (Show Source):
You can put this solution on YOUR website!
Given:
.
f%28x%29=abs%28x%29%2B7
.
Those "bars" surrounding x are absolute value signs. The purpose of absolute value signs
is to indicate that when the absolute value signs are removed, the quantity within them
gets changed to a positive value regardless of its sign it had when it was inside the
absolute value signs. [If the quantity inside the absolute value signs was plus, when the
absolute value signs are removed, it remains plus. However if the quantity in side the
absolute value signs was minus, when the absolute value signs are removed, it changes
from minus to plus.]
.
In this problem you are told to evaluate f(x) when x = -9. Substitute -9 for x and
f(x) becomes:
.
f%28-9%29+=+abs%28-9%29+%2B+7
.
Now recall the rule regarding the absolute value signs. Remove them, but change the sign
of the -9 so that it becomes +9. When you do that, the value of f(-9) becomes:
.
f%28-9%29+=+abs%28-9%29+%2B+7+=+9+%2B+7+=+16
.
Hope this helps you to understand the meaning of absolute value signs and how to use them
in problems such as this one.
.