Answer:
-2
Step-by-step explanation:
If a1 = 7 and an = An-1 – 3
a4 = a3 - 3
Get a2;
a2 = a1 - 3
a2 = 7 - 3
a2 = 4
Get a3;
a3 = a2 - 3
a3 = 4 - 3
a3 = 1
GEt the required a4
a4 = a3 - 3
a4 = 1 - 3
a4 = -2
Hence the value of a4 is -2
Absolute value is a function that takes some number and outputs the size of that number, regardless of the sign. By definition,
if
, and
if
.
For example,
- |2| = 2 because the input 2 is positive, so the input is unchanged;
- |-3| = -(-3) = 3 because the input -3 is negative, so the sign is switched.
What this means for this problem is that there are two cases to consider:
- If
, then
, so that

- On the other hand, if
, then
, so

(-x) - 18 is the correct answer.
Reasoning: FOUL the -3 with (x+6) to get -3x-18+2x, and then combine like terms.