If $\displaystyle a\in R, b\in R$, then the equation $\displaystyle x^{2}-abx-a^{2}=0$ has
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If $\displaystyle a\in R, b\in R$, then the equation $\displaystyle x^{2}-abx-a^{2}=0$ has
one positive root and one negative root
both root positive
both root negative
nonreal roots
To determine the nature of the roots, we evaluate the discriminant of the quadratic equation, which is $D = b^2 - 4ac$. Substituting the coefficients gives $(-ab)^2 - 4(1)(-a^2)$, simplifying to $a^2b^2 + 4a^2$, or $a^2(b^2 + 4)$. Because the square of any real number is non-negative, $D$ is strictly greater than zero, meaning the roots are real and distinct. Additionally, the product of the roots is $c/a = -a^2$, which is always negative, proving there is one positive root and one negative root.