Question Details

If 16 x 4 + 1 16 x 4 = 14159 , then find the value of 2 x + 1 2 x .

Options

A

12

B

11

C

15

D

9

Show Answer

Correct Answer :

Option B

11

Solution :

The correct answer is 11.

To find the value of 2x+12x, let us define a variable y=2x+12x.

First, we square this expression to find a relation with higher powers of x:
y2=2x+12x2
Using the algebraic identity (a+b)2=a2+b2+2ab, we expand:
y2=4x2+14x2+2·(2x)·12x
y2=4x2+14x2+2
From this, we get:
4x2+14x2=y2-2

Next, we square this expression again to relate it to the given term 16x4+116x4:
4x2+14x22=y2-22
Expanding the left side:
16x4+116x4+2·(4x2)·14x2=y2-22
16x4+116x4+2=y2-22

We are given that 16x4+116x4=14159. Substituting this value:
14159+2=y2-22
14161=y2-22

Taking the square root on both sides:
y2-2=14161
To find 14161, we observe that 1202=14400 and 1192=14161. Assuming positive values for real x:
y2-2=119
y2=119+2
y2=121

Finally, taking the square root:
y=121=11

Therefore, the value of 2x+12x is 11.

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