I learnt this in 5th

Algebra Level 3

3 x + 2 x + 1 3 x 2 x + 1 = 5 \dfrac{ \sqrt{3x} + \sqrt{2x+1} }{\sqrt{3x} - \sqrt{2x+1}} = 5

Find the value of x x satisfying the equation above.

Clarification: For this question, we are working over the complex numbers.


The answer is -1.5.

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5 solutions

Jaiveer Shekhawat
Nov 30, 2014

did you remember... Componendo and Dividendo???

09 09

Please refrain from posting inappropriate images. I have removed the image to this problem.

Calvin Lin Staff - 6 years, 6 months ago

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pp pp

jaiveer shekhawat - 6 years, 6 months ago

I learnt componendo and dividendo in class 5 th.. :P

jaiveer shekhawat - 6 years, 6 months ago

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did you also learnt complex no.s at same time!!!!!

Aakash Khandelwal - 6 years ago

I got quadratic equation after rationalizing and removing root sign.And I got answers as 1 and -1.5.For 1 our equation has zero in denominator.

shivamani patil - 6 years, 6 months ago

How is d=1?

Asad Jawaid - 4 years, 4 months ago

i learnt in class 7

vinayak kaushal - 1 year, 11 months ago

This should be easier:

3 x + 2 x + 1 3 x 2 x + 1 = 5 3 x + 2 x + 1 = 5 ( 3 x 2 x + 1 ) \dfrac {\sqrt{3x}+\sqrt{2x+1}}{\sqrt{3x}-\sqrt{2x+1}} = 5 \quad \Rightarrow \sqrt{3x}+\sqrt{2x+1} = 5(\sqrt{3x}-\sqrt{2x+1})

6 2 x + 1 = 4 3 x 3 2 x + 1 = 2 3 x 9 ( 2 x + 1 ) = 4 ( 3 x ) \Rightarrow 6\sqrt{2x+1} = 4\sqrt{3x} \quad \Rightarrow 3\sqrt{2x+1} = 2\sqrt{3x} \quad \Rightarrow 9(2x+1) = 4(3x)

18 x + 9 = 12 x 6 x = 9 x = 3 2 = 1.5 \Rightarrow 18x+9 = 12x \quad \Rightarrow 6x = -9 \quad \Rightarrow x = -\dfrac {3}{2} = \boxed{-1.5}

I did it the same way sir ! :)

Keshav Tiwari - 6 years, 6 months ago

My answer was the same! The only difference was that I wrote -3/2as my answer and the computer didn't accept it😂

Aarush Priyankaj - 2 years, 10 months ago

same here,

Aareyan Manzoor - 6 years, 6 months ago

Same here. :D

Rick B - 6 years, 6 months ago
Mihir John
Nov 30, 2014

But x=-1.5 cannot satisfy this equation because you cannot have negative values inside a square root. Hence this equation has no real solution.

pp pp

jaiveer shekhawat - 6 years, 6 months ago

It can by defining 1 = i \sqrt{-1} = i , the imaginary number. A number with both real and imaginary parts is a complex number.

Chew-Seong Cheong - 6 years, 6 months ago

also note that it is not required for numbers to be real (not specified in the question)

Abhinav Raichur - 6 years, 6 months ago

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But isn't x =-1.5 a real solution?

Mihir John - 6 years, 6 months ago

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i did not speak about solutions but instead i stated the fact that just because factors are imaginary doesn't mean that their product should follow ..... For example, you could factor x 2 x^{2} + 1 as (x + i)(x-i) { which is imaginary } .... that doesn't mean it is totally unreal.

Abhinav Raichur - 6 years, 6 months ago
Asad Jawaid
Jan 28, 2017

we should be a44ble to multiply [sqrt(3x) + sqrt(2x + 1)]/[sqrt(3x - sqrt(2x + 1)] by [sqrt(3x)+ sqrt(2x+1)]/[sqer(3x) + sqrt(2x+1)] =[(sqrt(3x)+sqrt(2x+1)]^2/[(3x -2x -1)]=5. Then 5(x-1) = 3x + 2sqrt(3x)sqrt(2x+1)+ 2x+1,or -6 =2sqrt(3x(2x+1), and 36 = 4(3x)(2x+1), 3 = 2x^2 + x, and 2x^2 +x -3 =0, 2x = -1 +/ sqrt(1 + 24),,2x=-6,4 Ed Gray

Edwin Gray - 4 years ago

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I cannot understand that working in computer code.

Asad Jawaid - 4 years ago
Betty BellaItalia
Jun 17, 2017

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