Datrys r^22(x^2-9)=90-x^2

$$r ^ { 2 } 2 ( x ^ { 2 } - 9 ) = 90 - x ^ { 2 }$$

Datrys ar gyfer r (complex solution)

$$r=-\frac{i\left(x^{2}-9\right)^{-\frac{1}{2}}\sqrt{2\left(x^{2}-90\right)}}{2}$$

$$r=\frac{i\left(x^{2}-9\right)^{-\frac{1}{2}}\sqrt{2\left(x^{2}-90\right)}}{2}\text{, }x\neq -3\text{ and }x\neq 3$$

Datrys ar gyfer x (complex solution)

$$x=-3i\left(2r^{2}+1\right)^{-\frac{1}{2}}\sqrt{-2r^{2}-10}$$

$$x=3i\left(2r^{2}+1\right)^{-\frac{1}{2}}\sqrt{-2r^{2}-10}\text{, }r\neq -\frac{\sqrt{2}i}{2}\text{ and }r\neq \frac{\sqrt{2}i}{2}$$

Datrys ar gyfer r

$$r=\frac{\sqrt{\frac{2\left(90-x^{2}\right)}{x^{2}-9}}}{2}$$

$$r=-\frac{\sqrt{\frac{2\left(90-x^{2}\right)}{x^{2}-9}}}{2}\text{, }\left(x>3\text{ and }x\leq 3\sqrt{10}\right)\text{ or }\left(x\geq -3\sqrt{10}\text{ and }x<-3\right)$$

Datrys ar gyfer x

$$x=3\sqrt{\frac{2\left(r^{2}+5\right)}{2r^{2}+1}}$$

$$x=-3\sqrt{\frac{2\left(r^{2}+5\right)}{2r^{2}+1}}$$