Knowing that
lim 3x + 2 = 8
x -> 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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To find the values of x that guarantee that f(x) is within a certain distance of 5, we can use the definition of a limit.
a. To find the values of x that guarantee f(x) is within 0.6 units of 5, we can set up the following inequality:
|f(x) - 5| < 0.6
Since f(x) = 3x + 2, we can substitute f(x) into the inequality:
|3x + 2 - 5| < 0.6
Simplifying the inequality, we get:
|-3 + 3x| < 0.6
Now we can solve the inequality for x:
-0.6 < -3 + 3x < 0.6
Adding 3 to all parts of the inequality:
2.4 < 3x < 3.6
Dividing all parts of the inequality by 3:
0.8 < x < 1.2
Therefore, the values of x that guarantee f(x) is within 0.6 units of 5 are 0.8 < x < 1.2.
b. To find the values of x that guarantee f(x) is within c units of 5, we can set up the following inequality:
|f(x) - 5| < c
Substituting f(x) = 3x + 2:
|3x + 2 - 5| < c
Simplifying the inequality:
|-3 + 3x| < c
Now we solve the inequality:
-c < -3 + 3x < c
Adding 3 to all parts of the inequality:
3 - c < 3x < c + 3
Dividing all parts of the inequality by 3:
(3 - c)/3 < x < (c + 3)/3
Therefore, the values of x that guarantee f(x) is within c units of 5 are (3 - c)/3 < x < (c + 3)/3.