Question : If $m$ and $n$ are two positive real numbers such that $9 m^2+n^2=40$ and $mn = 4$, then the value of $3m + n$ is:
Option 1: 160
Option 2: 64
Option 3: 10
Option 4: 8

Question

Question : If $m$ and $n$ are two positive real numbers such that $9 m^2+n^2=40$ and $mn = 4$, then the value of $3m + n$ is:

Option 1: 160

Option 2: 64

Option 3: 10

Option 4: 8

Team Careers360 · Accepted Answer

Correct Answer: 8

Solution : Given, $9 m^2+n^2=40$ and $mn = 4$
So, $9 m^2+n^2+6mn=40+6(4)$
⇒ $ (3m+n)^2=64$
⇒ $3m+n=8$
Hence, the correct answer is 8.

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Question : If $m$ and $n$ are two positive real numbers such that $9 m^2+n^2=40$ and $mn = 4$, then the value of $3m + n$ is:Option 1: 160Option 2: 64Option 3: 10Option 4: 8

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Question : If $m$ and $n$ are two positive real numbers such that $9 m^2+n^2=40$ and $mn = 4$, then the value of $3m + n$ is:
Option 1: 160
Option 2: 64
Option 3: 10
Option 4: 8