contestada

y is inversely proportional to x². When x=4, y=7.5 Find y when x=5 (i also forgot the symbol for directly and inversely proportional and i'm pretty sure there is one)

Respuesta :

Answer:

y = 4.8

Step-by-step explanation:

Given that y is inversely proportional to x² then the equation relating them is

y = [tex]\frac{k}{x^2}[/tex] ← k is the constant of proportion

To find k use the condition when x = 4, y = 7.5 , then

7.5 = [tex]\frac{k}{4^2}[/tex] = [tex]\frac{k}{16}[/tex] ( multiply both sides by 16 )

k = 16 × 7.5 = 120

y = [tex]\frac{120}{x^2}[/tex] ← equation of proportion

When x = 5 , then

y = [tex]\frac{120}{5^2}[/tex] = [tex]\frac{120}{25}[/tex] = 4.8