Manipulating Error

Algebra Level 4

If $x$ is a real number satisfying $\sqrt{x} =-x^2 - 1$ , find the value of $x^4 + 2x^2 - x$ .

0 1 No Solution -1

1 solution

Paul Ryan Longhas
Nov 20, 2015

Notice that $\sqrt{x} \geq 0$ and $-x^2 - 1 < 0$ which is a contradiction.

Why can't $\sqrt{x}$ be negative? $\sqrt{25}$ is either 5 or -5 for instance, both solutions being real.

Rajesh Kumar - 5 years, 6 months ago

Square root of any positve number always returns a positive value .

square root (25 ) = 5

but if x^2 = 25 then x = 5 or -5

Prakhar Bindal - 5 years, 6 months ago

Is it just me or does the question seem flawed to anyone else : If statement A is assumed to be true determine quantity B (in this case the solution would be -1).

As A is false a better option would be to say B cannot be determined or am I missing something??

Muneeb Yusufi - 5 years, 6 months ago

Almost did -1 there. But yeah I thought the same

Shreyash Rai - 5 years, 6 months ago

This is overrated, unfortunately.

Venkata Karthik Bandaru - 5 years, 5 months ago

way overrated actually

Shreyash Rai - 5 years, 5 months ago

Manipulating Error

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