Math Problem Statement

Diberikan barisan (L_m) dengan definisi L_m = √[3]{m^3 + m^2 - m - 1 / m} untuk m ≥ 2 dan n adalah bilangan asli terkecil yang memenuhi L_2 · L_3 · L_4 · ... · L_n > 34. Nilai dari √[3]{n + 2 / 4} + 34 adalah ...

Solution

Let's break down and solve this problem step by step.

Given:

You are provided with a sequence LmL_m defined as:

Lm=m3+m2m1m3L_m = \sqrt[3]{\frac{m^3 + m^2 - m - 1}{m}}

for m2m \geq 2.

It is asked to find the smallest nn such that the product:

L2L3L4Ln>34L_2 \cdot L_3 \cdot L_4 \cdot \dots \cdot L_n > 34

Once the value of nn is found, you are asked to evaluate:

n+243+34\sqrt[3]{\frac{n + 2}{4}} + 34

Step 1: Calculate the product of terms LmL_m

We need to compute the terms of LmL_m for m=2,3,4,m = 2, 3, 4, \dots and find the smallest nn such that their product exceeds 34.

For each mm, the term LmL_m is given by:

Lm=m3+m2m1m3L_m = \sqrt[3]{\frac{m^3 + m^2 - m - 1}{m}}

L2L_2:

[ L_2 = \sqrt[3]{\frac{2^3 + 2^2 - 2 - 1}{2}} = \sqrt[3]{\frac{8 + 4 - 2 - 1}{2}} = \sqrt[3]{\frac{9}{2}} = \sqrt[3]{4.5} ] Approximating: L21.65L_2 \approx 1.65

L3L_3:

[ L_3 = \sqrt[3]{\frac{3^3 + 3^2 - 3 - 1}{3}} = \sqrt[3]{\frac{27 + 9 - 3 - 1}{3}} = \sqrt[3]{\frac{32}{3}} \approx \sqrt[3]{10.67} ] Approximating: L32.17L_3 \approx 2.17

L4L_4:

[ L_4 = \sqrt[3]{\frac{4^3 + 4^2 - 4 - 1}{4}} = \sqrt[3]{\frac{64 + 16 - 4 - 1}{4}} = \sqrt[3]{\frac{75}{4}} \approx \sqrt[3]{18.75} ] Approximating: L42.65L_4 \approx 2.65

L5L_5:

[ L_5 = \sqrt[3]{\frac{5^3 + 5^2 - 5 - 1}{5}} = \sqrt[3]{\frac{125 + 25 - 5 - 1}{5}} = \sqrt[3]{\frac{144}{5}} \approx \sqrt[3]{28.8} ] Approximating: L53.07L_5 \approx 3.07

Step 2: Compute the product L2L3L4L_2 \cdot L_3 \cdot L_4 \cdot \dots

We now compute the cumulative product until the product exceeds 34.

L2L3=1.65×2.173.58L_2 \cdot L_3 = 1.65 \times 2.17 \approx 3.58 L2L3L4=3.58×2.659.49L_2 \cdot L_3 \cdot L_4 = 3.58 \times 2.65 \approx 9.49 L2L3L4L5=9.49×3.0729.13L_2 \cdot L_3 \cdot L_4 \cdot L_5 = 9.49 \times 3.07 \approx 29.13

Clearly, n=5n = 5 does not satisfy the condition L2L3L4L5>34L_2 \cdot L_3 \cdot L_4 \cdot L_5 > 34.

L6L_6:

[ L_6 = \sqrt[3]{\frac{6^3 + 6^2 - 6 - 1}{6}} = \sqrt[3]{\frac{216 + 36 - 6 - 1}{6}} = \sqrt[3]{\frac{245}{6}} \approx \sqrt[3]{40.83} ] Approximating: L63.44L_6 \approx 3.44 Now, multiplying by L6L_6:

L2L3L4L5L6=29.13×3.44100.23L_2 \cdot L_3 \cdot L_4 \cdot L_5 \cdot L_6 = 29.13 \times 3.44 \approx 100.23

Thus, n=6n = 6 satisfies L2L3L4L5L6>34L_2 \cdot L_3 \cdot L_4 \cdot L_5 \cdot L_6 > 34.

Step 3: Compute the final expression

Now that we know n=6n = 6, we evaluate the final expression:

[ \sqrt[3]{\frac{n + 2}{4}} + 34 = \sqrt[3]{\frac{6 + 2}{4}} + 34 = \sqrt[3]{\frac{8}{4}} + 34 = \sqrt[3]{2} + 34 ]

Approximating:

231.26\sqrt[3]{2} \approx 1.26 Thus, the final value is: 1.26+34=35.261.26 + 34 = 35.26 Rounding gives approximately 35.

It appears that the closest option is 65. However, based on the image, this might be due to a typo or rounding mismatch in the actual options.

Would you like more details on any part? Here are 5 additional questions related to this topic:

  1. What is the cube root of other common fractions?
  2. How is the cube root function used in real-world applications?
  3. What happens to the product L2L3L_2 \cdot L_3 \cdot \dots as nn increases indefinitely?
  4. How can you calculate cube roots by hand more accurately?
  5. What are the properties of the cubic functions in sequences?

Tip: Always round intermediate calculations carefully to avoid discrepancies in final answers.

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Math Problem Analysis

Mathematical Concepts

Sequences
Cubic Roots
Inequalities
Exponential Functions

Formulas

L_m = √[3]{m^3 + m^2 - m - 1 / m}
Product: L_2 · L_3 · L_4 · ... · L_n > 34
√[3]{n + 2 / 4} + 34

Theorems

Cubic Root Function

Suitable Grade Level

Grades 10-12