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Re: equation with fourth root [#permalink]
Test x = -2. We get: -2 = ∜(-2³ + 6*-2²) = ∜(16). DOESN’T work. Why? please explain .
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Re: equation with fourth root [#permalink]
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JelalHossain wrote:
Test x = -2. We get: -2 = ∜(-2³ + 6*-2²) = ∜(16). DOESN’T work. Why? please explain .



Square root of a number always gives the positive root.
For example,
x=√16 will be 4 and not -4.

To remember:

√x²=|x| (always)
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Re: equation with fourth root [#permalink]
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JelalHossain wrote:
Test x = -2. We get: -2 = ∜(-2³ + 6*-2²) = ∜(16). DOESN’T work. Why? please explain .


∜(any positive number) = some POSITIVE number

So, ∜(16) = 2 (not -2)
So, the equation -2 = ∜(16) does not hold true.

Does that help?

Cheers,
Brent
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Re: equation with fourth root [#permalink]
the answer is A right?
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Re: equation with fourth root [#permalink]
NoorJassem wrote:
the answer is A right?


Yes, that's correct.
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Re: equation with fourth root [#permalink]
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square root of a positive number can be positive and negative. Hence the answer is C
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Re: equation with fourth root [#permalink]
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This is incorrect the answer should be C.
(16)^1/2 has 2 solutions, 4 and -4
For a better representation, check the graphical representation of y = x^2. It is a parabola, with 2 x-intercepts(roots) centered around the y axis. The graph for y = x^4 is similar, except that is steeper because y rises faster than the run of x since it is a higher power.
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Re: equation with fourth root [#permalink]
How to know that whether it works or not?
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Re: equation with fourth root [#permalink]
Cant we consisder X^2 = t and then solve
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Re: equation with fourth root [#permalink]
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and once substituted then what ?
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Re: equation with fourth root [#permalink]
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