Answer:
A
Step-by-step explanation:
Using the substitution u = [tex]x^{\frac{1}{2} }[/tex]
noting that ([tex]\frac{1}{2}[/tex] )² = [tex]\frac{1}{4}[/tex], then
[tex]x^{\frac{1}{2} }[/tex] + 9[tex]x^{\frac{1}{4} }[/tex] + 20 = 0
Can be rewritten as
u + 9u² + 20 = 0, that is
9u² + u + 20 = 0 ← in standard form
