## Precalculus (6th Edition) Blitzer

Fill the blank with $\pm\sqrt{d}$
When we write $\sqrt{d}$, we mean the primary, positive square root of d. $(\sqrt{d})^{2}=d$ by the property of roots, but, also, $(-\sqrt{d})=(-1)^{2}(\sqrt{d})^{2}=d$ So, $u$ can be $+\sqrt{d}$ or $-\sqrt{d}$, which we write $\pm\sqrt{d}$. The square root property: If $u^{2}=d$ then $u=\pm\sqrt{d}$ Fill the blank with $\pm\sqrt{d}$