Solve for r
r=2k^{2}
k\neq 0
Solve for k
k=\frac{\sqrt{2r}}{2}
k=-\frac{\sqrt{2r}}{2}\text{, }r>0
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r=k\times 2k
Multiply both sides of the equation by 2k.
r=k^{2}\times 2
Multiply k and k to get k^{2}.
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