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If the value of “y” varies directly with “x” and y = -8 when x = 20, find “y” if x = -4.

If the value of y varies directly with x and y 8 when x 20 find y if x 4 class=

Respuesta :

Answer:

y = [tex]\frac{8}{5}[/tex]

Step-by-step explanation:

Given y varies directly with x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = - 8 when x = 20

k = [tex]\frac{y}{x}[/tex] = [tex]\frac{-8}{20}[/tex] = - [tex]\frac{2}{5}[/tex]

y = - [tex]\frac{2}{5}[/tex] x ← equation of variation

When x = - 4, then

y = - [tex]\frac{2}{5}[/tex] × - 4 = [tex]\frac{8}{5}[/tex]