That Root is Radical!

Algebra Level 1

What positive integer value of x x satisfies

2 12 x = 2 2 × ( 2 ) x + 1 ? \sqrt[x] { 2^{12} } = 2^2 \times \left( \sqrt{2} \right)^{x+1} ?


The answer is 3.

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8 solutions

You just change the root to expoential number. After that, its easy to evaluate this!

  1. Change the root to exponent, like this. Note : symbol of ^ is the exponent 2^12/X = 2^2 x 2^1/2(X+1) because general number already same, is 2, so, eliminate the number. like this : 12/X = 2 x (1/2 (X+1)) 12/X = 2 x (1/2X + 1/2) 12/X = X + 1 12 = X^2 + X so, it become X^2 + X -12, use factorization to solve this. (X+4) (X-3) or X = -4 and X= 3. because brilliant only admit the answer fron 0-999, it certainly 3 as an answer.

ur welcome :)

Arinilhaq Nafisah - 7 years, 10 months ago

O_O! i just simply typing "3" and it's correct in one try.

Stefanus Arya - 7 years, 10 months ago

Thanks a lot for your soluton . It was helpful .

Dhanya Nambiar - 7 years, 10 months ago

thanks!,:D

Lee Gadian - 7 years, 10 months ago

thanks, this is easy.

Erna Avita S - 7 years, 10 months ago

thank you, take it easy guys :) @arinilhaq

Arinilhaq Nafisah - 7 years, 10 months ago
Jebu Sultana
Aug 10, 2013

Let's start... Slightly rewriting, we get...

2 12 x = 2 2 × 2 x + 1 2 2 12 x = 2 x + 5 2 2^{\frac {12}{x}}=2^{2} \times 2^{\frac {x+1}{2}} \Longrightarrow 2^{\frac {12}{x}}=2^{\frac {x+5}{2}}

12 x = x + 5 2 x 2 + 5 x 24 = 0 ( x 3 ) ( x + 8 ) = 0 \Longrightarrow \frac {12}{x}= \frac {x+5}{2} \Longrightarrow x^2+5x-24=0 \Longrightarrow (x-3)(x+8)=0

Hence, the only positive integer solution to x x is 3 \fbox {3}

which book you do follow ?

CHIKU PRASAD Lenka - 7 years, 10 months ago
Lucas Matheus
Aug 4, 2013

2^12/x= 2^2+ 2^1/2.x+1/2 12/x= 5/2+1/2.x 12/x-1/2.x=5/2 -x²-5x+24=0 faz baskara e da -8 e 3, como pede o inteiro positivo, fica o 3!

Deepanshu Jangid
Aug 11, 2013

3

Connor Montoya
Aug 8, 2013

(x root of 2) ^ 12 = (2 ^ 2) * (squareroot of 2) ^ (x + 1):> I change the radical to an exponent to make managing the equation easier.:> 2 ^ (12 / x) = 4 * (squareroot of 2) ^ (x + 1):> Since 4 is (the squareroot of 2) ^ 4, and is being multiplied to a like term of (squareroot of 2) ^ (x + 1), I can add the exponents together to get::> 2 ^ (12 / x) = (squareroot of 2) ^ (x + 5).:> to make the terms the same on each side of the equation, I can convert the [2 ^ (12 / x)] to [(Squareroot of 2) ^ (24 / x)].:> (Squareroot of 2) ^ (24 / x) = (squareroot of 2) ^ (x + 5):> I knoticed that when x = 3, 3 + 5 = 8 and 8 * 3 = 24.:> (Squareroot of 2) ^ (24 / 3) = (squareroot of 2) ^ (3 + 5):> (Squareroot of 2) ^ (8) = (squareroot of 2) ^ (8):> 2 ^ 4 = 2 ^ 4:> 16 = 16:> x = 3:> solved

Mehwish Noor
Aug 6, 2013

compare the power of both sides 12/x =2+((x+1)/2) then solve equation for x and get answer

1 + 2 =3

Your answer seems to be so simple not like those other long solutions, but could you elobrate your answer please. I could'nt get the way , you just added 1 and 2 to get the answer . Hoping for a reply.

Dhanya Nambiar - 7 years, 10 months ago

Log in to reply

try with my technique, if u like :)

Arinilhaq Nafisah - 7 years, 10 months ago

Factor of 12 is = 1,2,3,4,6,12. And the only odd number is = 1 and 3. The answer must be = 3. (Don't use this techique on your exam)

Stefanus Arya - 7 years, 10 months ago

2^12/x=2^2 (2) 1/2(x+1) then calculate it.. it will be solved...

Simanta Deb - 7 years, 10 months ago
Abhishek Misra
Aug 5, 2013

2^(12/x)=2^2 (2^(x+1)/2) 2^(12/x)=2^(2+(x+1)/2) 2^(12/x)=2^((5+x)/2) 12/x=(5+x)/2 X^2+5 x-24=0 (x+8)(x-3)=0 x= -8 or x=3 hence positive integer of x=3

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