Every Problem Has A Solution, isn't it?

Algebra Level 4

x 2 4 x + 3 + x 2 9 = 4 x 2 14 x + 6 \sqrt{x^2 - 4x + 3} + \sqrt{x^2 - 9} = \sqrt{4x^2 - 14x + 6 }

How many solutions are there for the given equation?

Treat the square root as a real valued function.

1 2 No solutions 6 8 4

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1 solution

Callie Ferguson
Jul 30, 2019

EDIT: this solution is not correct, see Nikola Alfredi's solution for correction!

( x 1 ) ( x 3 ) \sqrt{(x-1)(x-3)} + ( x + 3 ) ( x 3 ) \sqrt{(x+3)(x-3)} = 2 ( 2 x 1 ) ( x 3 ) \sqrt{2(2x-1)(x-3)}

Notice that x 3 \sqrt{x-3} is a common factor in each of these terms.

x 3 \sqrt{x-3} [ x 1 [\sqrt{x-1} + x + 3 ] \sqrt{x+3}] = x 3 \sqrt{x-3} 2 ( 2 x 1 ) \sqrt{2(2x-1)}

Factoring that out, we can eliminate it from both sides of the equation:

x 1 \sqrt{x-1} + x + 3 \sqrt{x+3} = 2 ( 2 x 1 ) \sqrt{2(2x-1)}

Now, square both sides to get rid of the radicals:

( x 1 ) (x-1) + ( x + 3 ) (x+3) = 2 ( 2 x 1 ) 2(2x-1)

Finally, simplify the above equation to solve for x:

2 x + 2 = 4 x 2 2x+2=4x-2

4 = 2 x 4=2x

2 = x 2=x

Therefore, there is only one solution to the equation: x = 2 x=2

Solution isTerribly wrong.

Nikola Alfredi - 1 year, 1 month ago

How will you explain the squaring of two sides of equation will lead to square free terms in this case ? And more to it x = 3 is also a solution to the equation. You cannot directly cancel out the factors, please be sure of your actions... There will be two solutions to the question.

Nikola Alfredi - 1 year, 1 month ago

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You're right, x=3 does seem to be a solution. However, you could have informed me more kindly! I'll delete my solution, but only on the condition that you post the correct one :) Thanks for letting me know!

Callie Ferguson - 1 year, 1 month ago

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I appologize if I sounded rude. I really do!

Nikola Alfredi - 1 year ago

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