Q. Determine the following limit in simplest form. If the limit is infinite, state that the limit does not exist (DNE).x→∞lim7+8x+3x2331−27x6Answer:
Analyze Behavior: We are asked to find the limit of the function 7+8x+3x2331−27x6 as x approaches infinity. To do this, we will analyze the behavior of the numerator and the denominator separately as x grows without bound.
Consider Highest Powers: First, let's consider the highest power of x in the numerator and the denominator. In the numerator, the highest power inside the cube root is x6, and in the denominator, the highest power is x2. To simplify the limit, we will divide both the numerator and the denominator by x2, the highest power in the denominator.
Divide by x2: Dividing the numerator by x2 inside the cube root gives us 3x231−27x4. Dividing the denominator by x2 gives us x27+x8+3.
Simplify Numerator: As x approaches infinity, the terms x231 in the numerator and x27 and x8 in the denominator approach 0. So, we can simplify the limit to the leading terms, which gives us the limit of 33−27x4 as x approaches infinity.
Take Cube Root: Now, we can take the cube root of −27x4, which simplifies to −3x4/3. The limit now becomes the limit of 3−3x4/3 as x approaches infinity.
Divide by 3: We can simplify the expression further by dividing −3x34 by 3, which gives us −x34. So, the limit we are trying to find is now the limit of −x34 as x approaches infinity.
Simplify Further: Since x34 grows without bound as x approaches infinity, the limit of −x34 is negative infinity. Therefore, the limit does not exist.