Answer: b
Step-by-step explanation:Step 1: Simplify both sides of the equation.
6x=x2+9
Step 2: Subtract x^2+9 from both sides.
6x−(x2+9)=x2+9−(x2+9)
−x2+6x−9=0
Step 3: Factor left side of equation.
(−x+3)(x−3)=0
Step 4: Set factors equal to 0.
−x+3=0 or x−3=0