variation. within today

What is y'2 ?
It is assumed that y is raised to the power of 2. ( = y^2)
Correct me if I’m wrong.

(a)
Assign k is a constant of proportionality

y^2
z = k ------
x

(-2)^2 4k
4 = k ---------- = --------
3 3

k = 3

z is expressed in term x and y

3y^2
z = ------- (Answer)
x

(b)
If x =2 and y = 2

2^2
z = 3 ------ = 6
2

If x =1 and y = 1

1^2
z = 3 ------ = 3
1

Changes in z = final value of z – initial value of z
Changes in z = 3 – 6 = -3

Percentage change = (change in z/initial z) times 100% = (-3/6) (100) = -50%
Negative sign indicates it is decreasing.

Percentage change = -50% (z decreases by 50%)

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