Find the number of non-zero real solutions to the equation − x = x .
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Beautiful one!
But can't sqrt(1)=-1, and thus -sqrt(1)=1?
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No, 1 = − 1 , − 1 = 1 .
We define x as the principal square root function, this symbol represents the positive square root of x . x only yields two different results: either it is a non-negative number (for all x ≥ 0 ), or it is a complex number (for all x < 0 ). x can never give you a negative number
For the left hand to be defined, x has to be positive. The x is always positive or zero. Here it cannot be zero so it is positive. So the left hand side is always negative. The right hand side on the other hand is always positive as x is always positive. So there exists no non zero real solution to the equation.
Good approach of considering the domains and its implication.
I made the same approach!
For any x , its squared counterpart is always positive. Therefore, the answer is that there are 0 values that makes the equation true.
However, a more correct solution would be infinity because the question specified 'non-zero real number'. Since the square root of, let's say, 4 can be both 2 and - 2, the equation would be true for the negative root.
Note that x 2 = ∣ x ∣
x ≥ 0 ⟹ − x = x ≤ 0 On the other hand: x ≥ 0 ⟹ x ≥ 0 x ≤ 0 , x ≥ 0 ⟹ x = 0 Therefore x = 0 is the only real solution to this equation
Another way is to sketch the graph. Clearly there are only one point of intersection (which is at the origin), and hence the number of non-zero solutions is 0.
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− x = x x + x = 0 x ( x + 1 ) = 0
x = 0 ⟹ x = 0
x + 1 = 0 ⟹ x = − 1 ⟹ No real solution
Therefore, the only real solution of this equation is x = 0 . There are 0 non-zero real solutions for this equation