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1 vote
If y varies directly as x^2 and y = 144 when x = 4, what is the value of y when x = -5?

a.
-225
b.
225
c.
180
d.
-180


Please select the best answer from the choices provided

User Dhooonk
by
8.6k points

1 Answer

1 vote
As the variation is direct then we have the following expression:

y = kx ^ 2
From here, we clear the value of k.
For this we use the following data:
y = 144 when x = 4
Substituting values:

144 = k4 ^ 2
Clearing k we have:

k = 144/4 ^ 2 k = 144/16 k = 9
Then, the function is:

y = 9x ^ 2
When x = -5 we have:

y = 9 (-5) ^ 2 y = 9 (25) Y = 225
Answer:
the value of y when x = -5 is:
b.
225
User Remy Sharp
by
7.9k points

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