Question

y varies inversely with x . If y = 40 when x = 16 find x when y = -5​

Answer 1

Answer:

X = -128

Step-by-step explanation:

Since y varies inversely as x, y = k/x, for some number, k.

 

y = 40 when x = 16, so 40 = k/16. 

 

Therefore, k = 640

 

So, y = 640/x

 

When y = -5, we have -5 = 640/x

                       

Answer 2

Answer:

x = -128 when y = -5

Step-by-step explanation:

y varies inversely with x

Then, y ∝ 1/x ⇒ y = k/x ; where k is variation constant

Now y = 40 when x = 16

Then,. 40 = k/16 ⇒k = 40×16 ⇒ k = 640

Hence, y = 640/x

When y = -5 then, -5 = 640/x ⇒x = 640/(-5) ⇒x = -128