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For the natural numbers `n_1 and n_2` if `2n_1 + 3n_2 = n_1 xx n_2`, then the least possible value of the `2n_1 + 3n_2` is :

A

a. 6

B

b. 12

C

c. 24

D

d. can't be determined

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The correct Answer is:
To solve the equation \(2n_1 + 3n_2 = n_1 \times n_2\) for natural numbers \(n_1\) and \(n_2\) and find the least possible value of \(2n_1 + 3n_2\), we can use a systematic approach. ### Step 1: Rearranging the Equation We start with the equation: \[ 2n_1 + 3n_2 = n_1 \times n_2 \] We can rearrange it to: \[ n_1 \times n_2 - 2n_1 - 3n_2 = 0 \] ### Step 2: Expressing \(n_2\) in terms of \(n_1\) Rearranging gives us: \[ n_1 n_2 - 2n_1 = 3n_2 \] This can be rewritten as: \[ n_1 n_2 - 3n_2 = 2n_1 \] Factoring out \(n_2\): \[ n_2(n_1 - 3) = 2n_1 \] Thus, we can express \(n_2\) as: \[ n_2 = \frac{2n_1}{n_1 - 3} \] ### Step 3: Finding Natural Numbers For \(n_2\) to be a natural number, \(n_1 - 3\) must divide \(2n_1\). We will test different values of \(n_1\) starting from the smallest natural number greater than 3. #### Testing \(n_1 = 4\): \[ n_2 = \frac{2 \times 4}{4 - 3} = \frac{8}{1} = 8 \] Now we calculate \(2n_1 + 3n_2\): \[ 2n_1 + 3n_2 = 2 \times 4 + 3 \times 8 = 8 + 24 = 32 \] #### Testing \(n_1 = 5\): \[ n_2 = \frac{2 \times 5}{5 - 3} = \frac{10}{2} = 5 \] Calculating \(2n_1 + 3n_2\): \[ 2n_1 + 3n_2 = 2 \times 5 + 3 \times 5 = 10 + 15 = 25 \] #### Testing \(n_1 = 6\): \[ n_2 = \frac{2 \times 6}{6 - 3} = \frac{12}{3} = 4 \] Calculating \(2n_1 + 3n_2\): \[ 2n_1 + 3n_2 = 2 \times 6 + 3 \times 4 = 12 + 12 = 24 \] #### Testing \(n_1 = 7\): \[ n_2 = \frac{2 \times 7}{7 - 3} = \frac{14}{4} = 3.5 \quad (\text{not a natural number}) \] #### Testing \(n_1 = 8\): \[ n_2 = \frac{2 \times 8}{8 - 3} = \frac{16}{5} = 3.2 \quad (\text{not a natural number}) \] ### Conclusion The least possible value of \(2n_1 + 3n_2\) occurs when \(n_1 = 6\) and \(n_2 = 4\), giving us: \[ \text{Least possible value} = 24 \]
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