Løs left(a-3dright)^2+left(a-dright)^2+left(a+dright)^2+left(a+3dright)^2=20

$${ \left(a-3d \right) }^{ 2 } + { \left(a-d \right) }^{ 2 } + { \left(a+d \right) }^{ 2 } + { \left(a+3d \right) }^{ 2 } = 20$$

Løs for a (complex solution)

$$a=-\sqrt{5-5d^{2}}$$

$$a=\sqrt{5-5d^{2}}$$

Løs for d (complex solution)

$$d=-\frac{\sqrt{25-5a^{2}}}{5}$$

$$d=\frac{\sqrt{25-5a^{2}}}{5}$$

Løs for a

$$a=\sqrt{5-5d^{2}}$$

$$a=-\sqrt{5-5d^{2}}\text{, }|d|\leq 1$$

Løs for d

$$d=\frac{\sqrt{25-5a^{2}}}{5}$$

$$d=-\frac{\sqrt{25-5a^{2}}}{5}\text{, }|a|\leq \sqrt{5}$$