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Problem 8 - Entrance Test
Find the number of integers x that satisfy the inequality x^2 - 6x + 8 < 0 and |x - 3| <= 1.
Correct: B
We need to find the integers x that satisfy both inequalities.
First inequality: x^2 - 6x + 8 < 0
Factor the quadratic expression: (x - 2)(x - 4) < 0.
This inequality holds when x is between the roots 2 and 4.
So, 2 < x < 4.
The only integer satisfying this condition is x = 3.
Second inequality: |x - 3| <= 1
This absolute value inequality can be rewritten as:
-1 <= x - 3 <= 1
Add 3 to all parts of the inequality:
-1 + 3 <= x <= 1 + 3
2 <= x <= 4.
The integers satisfying this condition are x = 2, 3, 4.
Now, we need to find the integers that satisfy *both* conditions. We look for the intersection of the solution sets.
Solution set for first inequality: {3}
Solution set for second inequality: {2, 3, 4}
Intersection: {3} intersection {2, 3, 4} = {3}.
There is only 1 integer solution, which is x = 3.