Question

y varies inversely as twice x. When x = 4, y = 1. Find y when x = 5.

Answer 1

as it varies inversely:

y = k /2x where k is a constant

find the value of k by replacins x and y in the above by 4 and 1
so
1 = k / 2*4

now you can find the value of y

can you do this?

Answer 2

so 1=k/8?

Answer 3

right
so whats k?

Answer 4

multiply both sides of the equation by 8 will give you value of k

Answer 5

so 8?=k

Answer 6

k = 8
now replace k by 8to give the relation of y to x

y = 8 / 2x

Answer 7

and to find y when x = 5 just replace x in the above relation by 5
and calculate

Answer 8

these problems have 2 steps

1 find value of from data given to get the formula relating y to x
2 substitute value of 1 variable to get the other

Answer 9

* 1 find value of k

Answer 10

ok?

Answer 11

You can do it like this: