Knowing that
limit 3x + 2 = 5 as x approaching 1
what values of x guarantee that f(x) = 3x + 2 is within:
a. 0.6 units of 5?
b. c units of 5?
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a. To find the values of x that guarantee f(x) is within 0.6 units of 5, we can set up the inequality:
|f(x) - 5| ≤ 0.6
Substituting f(x) = 3x + 2:
|3x + 2 - 5| ≤ 0.6
Simplifying:
|3x - 3| ≤ 0.6
Now, we can solve this inequality. Splitting it into two cases:
Case 1: 3x - 3 ≤ 0.6
Adding 3 to both sides:
3x ≤ 3.6
Dividing both sides by 3:
x ≤ 1.2
Case 2: -(3x - 3) ≤ 0.6
Expanding the negative sign:
-3x + 3 ≤ 0.6
Subtracting 3 from both sides:
-3x ≤ -2.4
Dividing both sides by -3 (and remember that dividing by a negative number flips the inequality sign):
x ≥ 0.8
Combining the solutions from both cases:
0.8 ≤ x ≤ 1.2
Therefore, the values of x that guarantee f(x) is within 0.6 units of 5 are between 0.8 and 1.2 (inclusive).
b. To find the values of x that guarantee f(x) is within c units of 5, we can set up the inequality:
|f(x) - 5| ≤ c
Substituting f(x) = 3x + 2:
|3x + 2 - 5| ≤ c
Simplifying:
|3x - 3| ≤ c
Now, we can solve this inequality. Splitting it into two cases:
Case 1: 3x - 3 ≤ c
Adding 3 to both sides:
3x ≤ c + 3
Dividing both sides by 3:
x ≤ (c + 3)/3
Case 2: -(3x - 3) ≤ c
Expanding the negative sign:
-3x + 3 ≤ c
Subtracting 3 from both sides:
-3x ≤ c - 3
Dividing both sides by -3 (and remember that dividing by a negative number flips the inequality sign):
x ≥ (3 - c)/3
Combining the solutions from both cases:
(c + 3)/3 ≤ x ≤ (3 - c)/3
Therefore, the values of x that guarantee f(x) is within c units of 5 are between (c + 3)/3 and (3 - c)/3 (inclusive).