Desmos Graphing Calculator

CalcReferenceCopy

Math·Advanced Math·Nonlinear equations in one variable and systems of equations in two variables

hard

$$b^2+4c=9d$$The given equation relates the real numbers $b$, $c$, and $d$, where $9d>4c$. Which equation correctly expresses $b$ in terms of $c$ and $d$?

A

$b=\frac{9d+4c}{2}$

B

$b=\frac{9d-4c}{2}$

C

$b=\pm \sqrt{9d+4c}$

D

$b=\pm \sqrt{9d-4c}$