In short, Your Answer would be Option D) 25
Hope this helps!
Direct variation is y=kx where k is a constant
the fiest way to see if it is direct or not, is if x increases, then y increases as well,
then we see if y=kx is valid, basically if we have a constant of variation
the first one x increase and y increase
see if same constant
y=kx
-4.5=-3k
1.5=k
so
see next one
-1 and 3
-3=-1(k)
-3=-1(1.5)
-3=-1.5
false
not it
2nd is increase and y decrease, so not direct variation
3rd is x is same but y increase so nope
4th is x increase and y increase, now test the constant
-7.5=-3k
2.5=k
-1 and -2.5
-2.5=-1k
-2.5=-1(2.5)
-2.5=-2.5
true
answer is last option
if you have lets say 1/2/2/3
you flip the second fraction and multiply across
1/2*3/2
3/4
.75
To determine the centroid, we use the equations:
x⁻ =
1/A (∫ (x dA))
y⁻ = 1/A (∫ (y dA))
First, we evaluate the value of A and dA as follows:
A = ∫dA
A = ∫ydx
A = ∫3x^2 dx
A = 3x^3 / 3 from 0 to 4
A = x^3 from 0 to 4
A = 64
We use the equations for the centroid,
x⁻ = 1/A (∫ (x dA))
x⁻ = 1/64 (∫ (x (3x^2 dx)))
x⁻ = 1/64 (∫ (3x^3 dx)
x⁻ = 1/64 (3 x^4 / 4) from 0 to 4
x⁻ = 1/64 (192) = 3
y⁻ = 1/A (∫ (y dA))
y⁻ = 1/64 (∫ (3x^2 (3x^2 dx)))
y⁻ = 1/64 (∫ (9x^4 dx)
y⁻ = 1/64 (9x^5 / 5) from 0 to 4
y⁻ = 1/64 (9216/5) = 144/5
The centroid of the curve is found at (3, 144/5).