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7 votes
✎﹏Question~

• If 6(x2 + 1/x2) – 5(x + 1/x) = 38 and x is
positive and rational. then find the
value of x.

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User Atiqur
by
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1 Answer

27 votes
27 votes

Answer:

Sol: In this question, firstly we have to make the first bracket as a complete square of the second bracket. This we can by adding 2.x.1/x which is equivalent to 2. Then the equation becomes:

6(x2 + 1/x2 +2) – 5(x + 1/x) = 50 { 38 + 6*2)

⇒ 6(x2 + 1/x2 +2) – 5(x + 1/x) – 50 = 0

Now put x + 1/x = y

⇒ 6y2 -5y -50 = 0

⇒ (2y +5)(3y-10)= 0

⇒ y=-5/2 or 10/3

As x is positive therefore, x + 1/x =10/3

On solving further you will get as x=3 or 1/3

User Kittie
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