Answer
See below.
Work Step by Step
In terms of $c$: $c=a(x+b)^2$
In terms of $a$ (if $x\ne -b$): $c=a(x+b)^2\\a=\frac{c}{(x+b)^2}$
In terms of $b$: $c=a(x+b)^2\\(x+b)^2=\frac{c}{a}\\x+b=\pm\sqrt{\frac{c}{a}}\\b=\pm\sqrt{\frac{c}{a}}-x$
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